2017托福100篇阅读理解试题（二十）_第2页

　　5. The author mentions all of the following as examples of the effect of humans oil the world's ecosystems EXCEPT

　　(A) destruction of the tropical rain forests

　　(B) habitat destruction in wetlands

　　(C) damage to marine ecosystems

　　(D) the introduction of new varieties of plant species

　　6. The author mentions the extinction of the dinosaurs in the second paragraph to emphasize that

　　(A) the cause of the dinosaurs extinction is unknown

　　(B) Earth's climate has changed significantly since the dinosaurs' extinction,

　　(C) not all mass extinctions have been caused by human activity

　　(D) actions by humans could not stop the irreversible process of a species' extinction

　　7. The word "magnitude" in line 20 is closest in meaning to

　　(A) concern

　　(B) determination

　　(C) carelessness

　　(D) extent

　　8. According to the passage , natural evolutionary change is different from changes caused by humans in that changes caused by humans

　　(A) are occurring at a much faster rate

　　(B) are less devastating to most species

　　(C) affect fewer ecosystems

　　(D) are reversible

　　9. With which of the following statements would the author be most likely to agree?

　　(A) Human influence on ecosystems should not be a factor in determining public policy.

　　(B) The extinction of a few species is an acceptable consequence of human progress.

　　(C) Technology will provide solutions to problems caused by the destruction of ecosystems.

　　(D) Humans should be more conscious of the influence they have on ecosystems

　　参考答案：CBBCD CDAD