Question

Read the following passage and mark the letter A, B, tr or I) to indicate the correct answer to each of the questions from 36 to 42.

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 fanning. 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 is NOT given as an advantage of using biological agents over chemical herbicides?

A. They are safer for workers.

B. They are less likely to destroy desirable plants.

C. They are more easily available.

D. They do not have to be used as often.

Answer 1

Đáp án C

Dịch nghĩa: Câu nào sau đây không phải là một lợi ích của việc sử dụng tác nhân sinh học so với tác nhân hóa học?

A. An toàn cho sử dụng                               B. chúng ít khả năng làm hại những cây tốt

C. chúng có sẵn hơn.                                   D. Chúng không cần được sử dụng thường xuyên.

Giải thích: Phương án A, B và D đều được để cập trong bài, nhưng câu hỏi hỏi về KHÔNG nên chúng ta chọn C. Thông tin nằm ở đoạn 4 “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. Furthermore, a number of biological agents can be administered only once”