Câu hỏi:
27/04/2020 1,274Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 36 to 42
Since the dawn of time, people have found ways to communicate with one another. Smoke signals and tribal drums were some of the earliest forms of communication. Letters, carried by birds or by humans on foot or on horseback, made it possible for people to communicate larger amounts of information between two places. The telegram and telephone set the stage for more modern means of communication. With the invention of the cellular phone, communication itself has become mobile.
For you, a cell phone is probably just a device that you and your friends use to keep in touch with family and friends, take pictures, play games, or send text message. The definition of a cell phone is more specific: it is a hand- held wireless communication device that sends and receives signals by way of small special areas called cells.
Walkie - talkies, telephones and cell phones are duplex communication devices: They make it possible for two people to talk to each other. Cell phones and walkie- talkies are different from regular phones because they can be used in many different locations. A walkie- talkie is sometimes called a half- duplex communication device because only one person can talk at a time. A cell phone is a full- duplex device because it uses both frequencies at the same time. A walkie-talkie has only one channel. A cell phone has more than a thousand channels. A walkie- talkie can transmit and receive signals across a distance of about a mile. A cell phone can transmit and receive signals over hundreds of miles. In 1973, an electronic company called Motorola hired Martin Cooper to work on wireless communication. Motorola and Bell Laboratories (now AT& T) were in a race to invent the first portable communication device. Martin Cooper won the race and became the inventor of the cell phone. On April 3, 1973, Cooper made the first cell phone call to his opponent at AT& T while walking down the streets of New York city. People on the sidewalks gazed at cooper in amazement. Cooper's phone was called A Motorola Dyna- Tac. It weighed a whopping 2.5 pounds (as compared to today's cell phones that weigh as little as 3 or 4 ounces)
After the invention of his cell phone, Cooper began thinking of ways to make the cell phone available to the general public. After a decade, Motorola introduced the first cell phone for commercial use. The early cell phone and its service were both expensive. The cell phone itself cost about $ 3, 500. In 1977, AT & T constructed a cell phone system and tried it out in Chicago with over 2, 000 customers. In 1981, a second cellular phone system was started in the Washington,D.C and Baltimore area. It took nearly 37 years for cell phones to become available for general public use. Today, there are more than sixty million cell phone customers with cell phones producing over thirty billion dollars per years
When did Motorola introduce the first cell phones for commercial use?
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Trả lời:
Giải bởi Vietjack
Đáp án C
Motorola đã giới thiệu điện thoại di động đầu tiên cho mục đích thương mại khi nào?
A. Trong cùng một năm khi ông lần đầu tiên thực hiện một cuộc gọi điện thoại di động.
B. Năm 1981.
C. Năm 1983.
D. Trong cùng năm đó, AT & T đã xây dựng một hệ thống điện thoại di động
Nhà sách VIETJACK:
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 1:
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions
For ______, it is certain that in the future some things will be very different
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Câu 2:
Mark the letter A, B, C, or D on your answer sheet to indicate the word or phrase that is OPPOSITE in meaning to the underlined part in each of the following questions
We have to husband our resources to make sure we make it through these hard times
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28,880
Câu 3:
Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines of each pair of sentences in the following questions
We had spent nearly all our money. So we couldn’t afford to stay in a hotel
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27/04/2020
25,932
Câu 4:
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions
I know you have been working very hard today. Let's ________ and go home
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27/04/2020
23,562
Câu 5:
Mark the letter A, B, C, or D on your answer sheet to show the underlined part that needs correction
From bones finding in the United States, we have learned that many animals which no longer existed in the world once made their homes there
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27/04/2020
15,683
Câu 6:
Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions
John was praised for his bravery, ________ his colleagues were criticized for their cowardice
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27/04/2020
9,433
Câu 7:
Mark the letter A, B, C or D on your answer sheet to indicate the word that is pronounced differently from the rest in each of the following questions
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27/04/2020
8,321
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