2. Which of the following best interprets the meaning of “While the chimps worked out ” （the first sentence of the third paragraph）？

　　A While the chimps worked in the lab

　　B While the chimps exercised in the gym

　　C While the chimps tried to figure out what they should do

　　D While the chimps tried to understand the instructions

　　3. What was the result of the finding，according to Paragraph 5？

　　A Three chimps used more energy walking on two legs.

　　B One chimp used less energy walking on two legs.

　　C One chimp used about the same energy walking on two legs as on four.

　　D All of the above.

　　4. What was true of the hypothesis of the research？

　　A Our apelike ancestors were anatomically different but had the same gaits.

　　B Bipeds with natural selection had an advantage over quadruped.

　　C Our apelike ancestors could adapt to different climate changes due to genetic variation.

　　D Bipeds had an advantage over quadrupeds due to changes in the environment.

　　5. What does fossil and molecular evidence tell us about our earliest ancestors？

　　A They experienced more climate changes than we do today.

　　B Due to changes in climate，they were forced to travel between food patches.

　　C They could cover more ground than their quadrupedal peers because they used less energy.

　　D They could travel longer distances on the ground than those who could use less energy.

　　答案與題解：

　　1. C 短文的第一段直接回答了這個問題。

　　2. B worked out在此是“運(yùn)動，鍛煉”的意思，所以選擇B.

　　3. D 第五段的第三、第四和第五句提供了答案。bipedalism was more expensive的意思是：兩足行走消耗更多的體能。walking upright的意思是：直立行走，即兩足行走。

　　4. B 第六段告訴了我們研究的兩個假設(shè)：猿人祖先在解剖學(xué)意義上存在著差異，這一差異影響了它們的步態(tài)；這些差異在自然選擇的過程中決定了遺傳變異，而環(huán)境變化使得兩足行走的猿人比起四足行走的猿人更有戰(zhàn)勢。A、C、D都不是正確的說法，只有B在該段中被提到。

　　5. C 倒數(shù)第二段提供了問題的答案。travel longer distances用的是比較級，這里是將兩足行走的猿人與上文中四足行走的猿人做比較。those who could cover more ground using less energy指的是上文提到的與四足行走的猿人相比，體能消耗較小的兩足行走猿人。其他選擇都不是正確說法。