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Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34       According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).       Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.       For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.            Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcoholAccording to the passage, how is alcohol finally returned to the mother's system? 

Xem chi tiết 573 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34       According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).       Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.       For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.            Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcoholIt can be inferred that the development of a fetal liver depends on ___________ 

Xem chi tiết 523 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34       According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).       Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.       For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.       Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcohol.  How much time can it be inferred that it takes alcohol to enter a woman's bloodstream after she takes a drink?  

Xem chi tiết 1.3 K lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34       According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).       Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.       For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.            Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcoholThe word “its” in paragraph 2 refers to___________  

Xem chi tiết 553 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C or D to indicate the correct answer to each of the questions from 30 to 34       According to the American College of Obstetrics and Gynecology, pregnant women should not drink any form of alcohol. Pregnant women who think they have should be aware of the serious and negative effects alcohol on the development of the baby (fetus).       Alcohol is considered one of the most dangerous drugs for women during their pregnancy. Because alcohol is delivered quickly into the blood and passes quickly into the tissues and membranes, the human fetus is particularly vulnerable to its effects. The reality is that the negative effects on a fetus are so pronounced that babies born after exposure to alcohol are said to be suffering from fetal the syndrome. As a pregnant woman drinks alcohol, the alcohol is passed into her bloodstream almost simultaneously. Moreover, because the bloodstream of the fetus is inextricably tied to that of the mother, the alcohol passes directly into the bloodstream of the fetus as well. And, what is more, the concentration of alcohol in the fetus is exactly the same as in the mother.       For the mother, this concentration is not a problem because her liver can remove one ounce of alcohol from her system per hour. However, the fetus's liver is not completely developed (how developed it is depends on its stage of development). The rate at which it is able to eliminate the alcohol from the blood of the fetus is much slower. Eventually, the alcohol will be returned to the mother's system by passing across the placenta, but this process is slow. By the time this takes place, major neurological damage may have already occurred.            Research has shown that as little as one drink of alcohol can produce significant, irreversible damage to the fetus. Babies born after exposure to alcohol generally exhibit facial distortion, inability to concentrate, and difficulty in remembering. Simply speaking, it is imperative that pregnant women avoid alcoholWhat is the main topic of this reading?  

Xem chi tiết 693 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceased.Most of the helium in the universe was formed___________ 

Xem chi tiết 780 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedThe creation of helium within stars___________ 

Xem chi tiết 506 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedThe word "vary" is closest in meaning to___________ 

Xem chi tiết 411 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedThe word “they” refers to___________ 

Xem chi tiết 422 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedWhy does the author mention "cosmic rays"?  

Xem chi tiết 438 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedThe word "constituents” is closest in meaning to___________ 

Xem chi tiết 490 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedAccording to the passage, helium is ___________ 

Xem chi tiết 539 lượt xem 4 năm trước

Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions from 35 to 42       The elements other than hydrogen and helium exist in such small quantities that it is accurate to say that the universe is somewhat more than 25 percent helium by weight and somewhat less than 75 percent hydrogen.       Astronomers have measured the abundance of helium throughout our galaxy and in other galaxies as well. Helium has been found in old stars, in relatively young ones, in interstellar gas, and in the distant objects known as quasars. Helium nuclei have also been found to be constituents of cosmic rays that fall on the earth (cosmicrays are not really a form of radiation; they consist of rapidly moving particles of numerous different kinds). It doesn't seem to make very much difference where the helium is found. Its relative abundance never seems to vary much. In some places, there may be slightly more of it; in others, slightly less, but the ratio of helium to hydrogen nuclei always remains about the same.       Helium is created in stars. In fact, nuclear reactions that convert hydrogen to helium are responsible for most of the energy that stars produce. However, the amount of helium that could have been produced in this manner can be calculated, and it turns out to be no more than a few percent. The universe has not existed long enough for this figure to be significantly greater. Consequently, if the universe is somewhat more than 25 percent helium now, then it must have been about 25 percent helium at a time near the beginning.            However, when the universe was less than one minute old, no helium could have existed. Calculations indicate that before this time temperatures were too high and particles of matter were moving around much too rapidly. It was only after the one-minute point that helium could exist. By this time, the universe had cooled so sufficiently that neutrons and protons could stick together. But the nuclear reactions that led to the formations of helium went on for only relatively short time. By the time the universe was a few minutes old, helium production had effectively ceasedWhat does the passage mainly explain?  

Xem chi tiết 366 lượt xem 4 năm trước