Question

Read 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

It is estimated that over 99 percent of all species that have existed have become extinct. What causes extinction? When a species is no longer adapted to a changed environment, it may perish. The exact causes of a species' death vary from situation to situation. Rapid ecological change may render an environment hostile to a species. For example, temperatures may change and a species may not be able to adapt. Food resources may be affected by environmental changes, which will then cause problems for a species requiring these resources. Other species may become better adapted to an environment, resulting in competition and, ultimately, in the death of a species.

The fossil record reveals that extinction has occurred throughout the history of Earth. Recent analyses have also revealed that on some occasions, many species became extinct at the same time- a mass extinction. One of the best-known examples of mass extinction occurred 65 mmion years ago with the demise of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass extinction can be caused by a relatively rapid change in the environment and can be worsened by the close interrelationship of many species. If, for example, something were to happen to destroy much of the plankton in the oceans, then the oxygen content of Earth would drop, affecting even organisms not living in the oceans. Such a change would probably lead to a mass extinction.

One interesting, and controversial, finding is that extinctions during the past 250 million years have tended to be more intensive every 26 million years. This periodic extinction might be due to intersection of the Earth's orbit with a cloud of comets, but this theory is purely speculative. Some researchers have also speculated that extinction may often be random. That is, certain species may be eliminated and others may survive for no particular reason. A species' survival may have nothing to do with its ability or inability to adapt. If so, some of evolutionary history may reflect a sequence of essentially random events. 

What does the author say in paragraph 1 regarding most species in Earth's history?

A. They have been able to adapt to ecological changes

B. They have caused rapid changes in the environment

C. They have remained basically unchanged from their original forms

D. They are no longer in existence

Answer 1

Kiến thức: Đọc hiểu

Giải thích:

Ở đoạn 1, tác giả đã nói gì liên quan đến sinh vật trong lịch sử Trái đất ?

A. Họ đã có thể thích nghi với những thay đổi sinh thái.

B. Chúng đã gây ra những thay đổi nhanh chóng trong môi trường.

C. Về cơ bản chúng vẫn không thay đổi so với dạng ban đầu của chúng.

D. Chúng không còn tồn tại.

Thông tin: It is estimated that over 99 percent of all species that ever existed have become extinct.

Tạm dịch: Ước tính được rằng, có khoảng hơn 99 phần trăm các loài sinh vật đang tồn tại có nguy cơ tuyệt chủng.

Chọn D