Câu hỏi:
30/03/2020 262Read 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.
Humans have struggled against weeds since the beginnings of agriculture. Marring our gardens is one of the milder effects of weeds - any plants that thrive where they are unwanted. They clog waterways, destroy wildlife habitats, and impede farming. Their spread eliminates grazing areas and accounts for one-third of all crop loss. They compete for sunlight, nutrients, and water with useful plants.
The global need for weed control had been answered mainly by the chemical industry. Its herbicides are effective and sometimes necessary, but some pose serious problems, particularly if misused. Toxic compounds threaten animal and public health when they accumulate in food plants, groundwater, and drinking water. They also harm workers who apply them.
In recent years, the chemical industry has introduced several herbicides that are more ecologically sound. Yet new chemicals alone cannot solve the world's weed problems. Hence, scientists are exploring the innate weed-killing powers of living organisms, primarily insects and microorganisms.
The biological agents now in use are environmentally benign and are harmless to humans. They can be chosen for their ability to attack selected targets and leave crops and other plants untouched. In contrast, some of the most effective chemicals kill virtually all the plants they come in contact with, sparing only those that are naturally resistant or have been genetically modified for resistance. Furthermore, a number of biological agents can be administered only once, after which no added applications are needed. Chemicals typically must be used several times per growing season.
Which of the following terms does the author define in the first paragraph?
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Trả lời:
Giải bởi Vietjack
Đáp án : A
Thông tin ở câu thứ 2 đoạn đầu tiên: “one of the milder effects of weeds - any plants that thrive where they are unwanted.”
Nhà sách VIETJACK:
CÂU HỎI HOT CÙNG CHỦ ĐỀ
Câu 2:
Mark the letter A, B, C or D on your answer sheet to show the underlined part that needs correction in each of the following questions.
Animals and man (A) use the energy finding (B) in food to operate (C) their body and (D) muscles.
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Câu 3:
The weather is going to change soon; I feel it in my _________ .
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Câu 4:
Mark the letter A, B, C or D on your answer sheet to show the underlined part that needs correction in each of the following questions.
Not until much (A) later did she realize (B) that her long-known (C) partner had been lying her. (D)
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