注释：
1. UC Davis：加州大学戴维斯分校。UC是University of California（加利福尼亚大学）的缩写，该校有多个分校，UC Davis是其中一个。Davis以前是UC Berkeley分校的农学院，后来独立小来。Davis是一个大学城，很小的城市，Davis校园基本就构成了这个城市。
2. quadrupedal andbipedal：quad-：构词词素，是“四”的意思；bi-：构词词素，是“二”的意思； ped-：构词词素，是“脚”的意思；-al是构成形容词的后缀，表示“……的”。因此，quadrupedal 意为“凹足动物的”，bipedal意为“二足动物的”。
3. bipedalism：系bipedal（二足动物的）的对应名词，这里后缀-ism表示“特征”、“特性”。
练习：
1. What did Michael Sockol and his team find out in their study of chimpanzees？
A Tile evidence why chimpanzees can be trained to use treadmills.
B The evidence why our apelike ancestors came to walk on four legs.
C The evidence why our apelike ancestors came to walk on two legs.
D The evidence why chimpanzees can be trained to walk on two legs.
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.
标准答案： C，B，D，B，C