GWD 31 Q20-23我全错，不知道怎么定位啊。看不懂。只有几天就要考试了，帮帮我吧

Sherry茜

GWD-31-Q20-Q23

Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools, which they had begun to make as the species evolved a brain of increased size and mental capacity. But discoveries of the three-million-year-old fossilized remains of our hominid ancestor Australopithecus have yielded substantial anatomical evidence that upright walking appeared prior to the dramatic enlargement of the brain and the development of stone tools.

Walking on two legs in an upright posture (bipedal locomotion) is a less efficient proposition than walking on all fours (quadrupedal locomotion) because several muscle groups that the quadruped uses for propulsion must instead toprovide the biped with stability and control. The shape and configuration of various bones must likewise be modified to allow the muscles to perform these functions in upright walking. Reconstruction of the pelvis (hipbones) and femur (thighbone) of “Lucy”, a three-million-year-old skeleton that is the most complete fossilized skeleton from the australopithecine era, has shown that they are much more like the corresponding bones of the modern human than like those of the most closely related living primate, the quadrupedal chimpanzee. Lucy’s wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which evolved to form the larger birth canal needed to accommodate the head of a large-brained human infant. By contrast, the head of Lucy’s baby could have been no larger than that of a baby chimpanzee.

If the small-brained australopithecines were not toolmakers, what evolutionary advantage did they gain by walking upright? One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring. Walking upright permitted the father to use his hands to gather food and carry it to his mate from a distance, allowing the mother to devote more time and energy to nurturing and protecting their children. According to this view, the transition to bipedal walking may have occurred as long as ten million years ago, at the time of the earliest hominids, making it a crucial initiating event in human evolution.

20: The passage suggests that proponents of the theory mentioned in lines 50-54 (One theory is … offspring) assume that which of the following steps in human evolution occurred most recently?

A.development of a nuclear family structure

B.transition from walking on all fours to walking upright错
C.dramatic enlargement of the brain
D.use of the hands to gather and carry food
E.modification of propulsive muscles to provide stability and control in locomotion
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21: The passage suggests that, in comparison with the hominid australopithecines, modern humans are
A.less well adapted to large group cooperation
B.less well adapted to walking upright
C.more agile in running and climbing错
D.more well suited to a nuclear family structure
E.more well suited to cooperative caring for their offspring
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22: According to the passage, the hominid australopithecine most closely resembled a modern human with respect to which of the following characteristics?
A.brain size错
B.tool making ability
C.shape of the pelvis
D.method of locomotion
E.preference for certain foods
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23: The primary purpose of the passage is to

A.present an interpretation of the chronological relationship between bipedal locomotion and certain other key aspects of human evolution
B.compare the evolutionary advantages and disadvantages of bipedal locomotion to those of quadrupedal locomotion错
C.argue that the transition to a nuclear family structure was a more crucial step in human evolution than was the development of stone tools
D.analyze anatomical evidence of bipedal locomotion to show that the large brain of modern humans developed at a later stage of evolution than was previously believed
E.use examples of muscle and bone structure to illustrate the evolutionary differences between modern humans, australopithecines, and chimpanzees

上面红字是正确答案，错字代表我的答案。我怎么都错啊，这篇我真不懂，那位NN帮我解答一下好吗？只有几天就要考试了。多谢多谢多谢啊！！

终于悲催了

非牛菜鸟一只......
我觉得，除了最后一道（因为我也错了），前面几道题都可以用逻辑简图做出来，就是你一边看一边做笔记，这篇文章首段里有个转折，后面一直在提供证据，那就是个否旧推新式文章（我自己的归类....），那么文章的主旨就是新观点是什么。
文章说
过去：先脑大，再直立
现在：先直立，再脑大
直立不好动，骨头还要整，lucy直立了，但脑不大。
直立好处是：顾家
所以直立先出现，10million前
前几题就解出来了（学校今天11点半断电熄灯哈，来不及细说......）
全文一直在讲直立、脑大、顾家（男女分工），所以它的目的是讨论几个之间的关系~
不知道有没有帮助，要是你还没考，希望能帮得上你，要是你已经要考了，祝你顺利~