参考答案：
1.C.该题可以利用文章主题内容直接判断答案，也可以利用问题句及被选项中的特征结构及细节信息结构(加粗字体内容)共同作为答案线索， 在文章中查找答案相关句：
(可能的考点句)A team of (一组)scientists (科学家)that studied chimpanzees trained to use treadmills (跑步机)has gathered(收集，集合) new evidence (证据)suggesting(表明)that our earliest (初期的)apelike(象猿人的) ancestors(象猿人的) started(开始) walking on two legs because(因为) it required(需要， 要求) less(较少的) energy(能量)than getting around (到处走动)on all fours(四肢). (一组研究被训练学习使用跑步机的黑猩猩的科学家们发现了一些新的证据：我们的人猿祖先开始直立行走是因为两条腿比四条腿行走省力)
“When our earliest ancestors started walking on two legs, they took the first steps toward becoming human,” said lead(领导) researcher(研究带头人) Michael Sockol of UC Davis1. “Our findings help answer why.” Sockol worked for two years to find an animal trainer willing to coax adult chimps to walk on two legs and to “knucklewalk” on all fours on the sort of treadmill found in most gyms.
根据第一段的内容(一组研究被训练学习使用跑步机的黑猩猩的科学家们发现了一些新的证据：我们的人猿祖先开始直立行走是因为两条腿比四条腿行走省)可以直接判断C是答案。
2.B. 首先找到这个结构在文章中的位置，然后借助其所在句子的句意或上下文内容判断答案。
(第3段)The five chimps also wore face masks used to help the researchers measure oxygen consumption. While the chimps worked out, the scientists(科学家) collected(收集， 聚集) metabolic(新陈代谢的) and other data(数据) that allowed(允许) them to calculate(计算出) which method(方法) of locomotion(运动， 移动) used less energy(能量) and why. The team gathered the same information for four adult humans walking on a treadmill.
2. B worked out句子中的含义是“运动，锻炼”的意思，所以选择 B。
3.D. 利用被选项中的特征结构(加粗文字内容)作为答案线索，在文章中查找答案相关句：
(可能的考点设置句)(第5段)“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling. For three chimps, bipedalism(两足动物/具有两足动物特征) was more expensive(昂贵的， 花费的) (与选项A内容一致), but for the other two chimps, this isn’t the case(情况). One (代词， 指代one chimp)spent about the same energy(能量) walking on two legs as on four(与选项C一致). The other(指剩下的一个黑猩猩) used less energy walking upright(竖直地，垂直的， 正直的).(与选项B一致)”These two chimps had different gaits and anatomy than their knuckle walking peers.
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：两足行走消耗更多的体能。walking upright的意思是：直立行走，即两足行走。
4.D.利用问题句及被选项中的细节信息词语(加粗字体内容)共同作为答案线索， 在文章中查找答案相关句:
“We were prepared to find that all of the chimps used more energy walking on two legs – but that finding wouldn’t have been as interesting,” Sockol said. “What we found was much more telling.(第5段答案相关句) For three chimps, bipedalism3 was more expensive, but for the other two chimps, this wasn’t the case. One spent about the same energy walking on two legs as on four. The other used less energy walking upright.” These two chimps had different gaits and anatomy than their knucklewalking peers.
(可能的考点设置句)(第6段)Taken(拿， 拿走, 占领, 获得) together(一起), the findings(研究发现) provide support for (为...提供了支持)the hypothesis (假设)that anatomical (解剖学上的)differences(差异)affecting gait existed among(在...之中) our earliest apelike ancestors(与A不一致), and that these differences(差异) provided(提供) the genetic variation(遗传变异) which natural selection (自然选择)could act on(对...起作用)when changes in the environment(环境) gave bipeds(两足动物) an advantage over(优于...的优势) quadrupeds(四足动物)(该部分内容与选项D结构和用词一致， 因此D是答案).
第六段告诉了我们研究的两个假设：一种假设：猿人祖先在解剖学意义上存在着差异，这一差异影响了它们的步态;另一种假设：这些差异为自然选择所决定的遗传变异提供了可能性，而环境变化使得两足行走的猿人比起四足行走的猿人更有优势。因此B是答案。
5.C. 利用问题句及被选项中的细节信息结构(字体加粗文字)共同作为答案线索，在文章中查找答案相关句
(第4题答案相关句)Taken together, the findings provide support for the hypothesis that anatomical differences affecting gait existed among our earliest apelike ancestors, and that these differences provided the genetic variation which natural selection could act on when changes in the environment gave bipeds an advantage over quadrupeds.
Fossil(化石的) and molecular (分子的)evidence(证据) suggests(显示) the earliest ancestors(祖先) of the human family lived in forested(被森林所覆盖的) areas in equatorial(近赤道的) Africa(非洲) in the late(迟的，末期的) Miocene era (中世纪末期)some(大约) 8 to 10 million years ago(以前), when changes in climate may have increased the distance between food patches. That would have forced(强迫) our earliest ancestors(早期的祖先)(问题句中的核心结构) to travel longer distances(距离) on the ground and favored(赞成，帮助， 有利于) those who could cover(通过) more ground using less energy. (C中的cover more ground的近义结构travel longer distance , less energy都出现这个句子中，因此可能C是答案)。
“This isn’t the complete answer,” Sockol said. “But it’s a good piece of a puzzle humans have always wondered about: How and why did we become human? And why do we alone walk on two legs?”
倒数第二段提供了问题的答案。travel longer distances用的是比较级，这里是将两足行走的猿人与上文中四足行走的猿人做比较。those who could cover more ground using less energy指的是上文提到的与四足行走的猿人相比，体能消耗较小的两足行走猿人。其他选择都不是正确说法。
