托福阅读常考话题及练习题推荐一：恐龙大灭绝（2）

1托福阅读常考话题-恐龙大灭绝练习题

Paragraph 1: Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today’s. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.

1. According to paragraph 1, which of the following is true of the Late Cretaceous climate?

A. Summers were very warm and winters were very cold.

B. Shallow seas on the continents caused frequent temperature changes.

C. The climate was very similar to today’s climate.

D. The climate did not change dramatically from season to season.

Paragraph 2: At the end of the Cretaceous, the geological record shows that these seaways retreated from the continents back into the major ocean basins. No one knows why. Over a period

of about 100,000 years, while the seas pulled back, climates around the world became dramatically more extreme: warmer days, cooler nights; hotter summers, colder winters. Perhaps

dinosaurs could not tolerate these extreme temperature changes and became extinct.

2. Which of the following reasons is suggested in paragraph 2 for the extinction of the dinosaurs?

A. Changes in the lengths of the days and nights during the late Cretaceous period

B. Droughts caused by the movement of seaways back into the oceans

C. The change from mild to severe climates during the Late Cretaceous period

D. An extreme decrease in the average yearly temperature over 10,ooo years

Paragraph 3: If true, though, why did cold-blooded animals such as snakes, lizards, turtles, and crocodiles survive the freezing winters and torrid summers? These animals are at the mercy of the climate to maintain a livable body temperature. It’s hard to understand why they would not be affected, whereas dinosaurs were left too crippled to cope, especially if, as some scientists believe,dinosaurs were warm-blooded. Critics also point out that the shallow seaways had retreated from and advanced on the continents numerous times during the Mesozoic, so why did the dinosaurs survive the climatic changes associated with the earlier fluctuations but not with this one?

Although initially appealing, the hypothesis of a simple climatic change related to sea levels is insufficient to explain all the data.

3. Why does the author mention the survival of “snakes, lizards, turtles, and crocodiles” in paragraph 3?

A. To argue that dinosaurs may have become extinct because they were not cold-blooded animals

B. To question the adequacy of the hypothesis that climatic change related to sea levels caused the extinction of the dinosaurs

C. To present examples of animals that could maintain a livable body temperature more easily than dinosaurs

D. To support a hypothesis that these animals were not as sensitive to climate changes in the Cretaceous period as they are today

4. The word “cope” in the passage is closest in meaning to

A. adapt

B. move

C. continue

D. compete

5. According to paragraph 3, which of the following is true of changes in climate before the Cretaceous period and the effect of these changes on dinosaurs?

A. Climate changes associated with the movement of seaways before the Cretaceous period did not cause dinosaurs to become extinct.

B. Changes in climate before the Cretaceous period caused severe fluctuations in sea level,resulting in the extinction of the dinosaurs.

C. Frequent changes in climate before the Cretaceous period made dinosaurs better able to maintain a livable body temperature.

D. Before the Cretaceous period there were few changes in climate, and dinosaurs flourished.

6.The word “fluctuations” in the passage is closest in meaning to

A. extremes

B. retreats

C. periods

D. variations