quickly - you're late. I want you to freestyle while I talk to your mom."

　　I think that was the fastest I'd ever gotten into a pool. But if I thought that was bad, then I had another thing coming.

　　Each day for the next week, the swimming training was so grueling that I could barely get myself out of the pool after the two-hour class. My coach would yell at me whenever I did something wrong or I was hesitant to perform a task. During the day I was so nervous about this woman, that even at school, I was constantly planning what to say and do at swim practice.

　　The only reason I stayed as long as I did was because of one girl, whom I met around two weeks into the program. People didn't really want to talk when I tried to

reach out to them. But this girl saw that I was alone and sat next to me while we were stretching .

　　I "survived" the training because I had someone who could cheer me on and someone that I could have fun with but also be serious with. We stood up for each other when the coach called us out. Sometimes, it felt like it was us against the world when we were on that team. So finally, when we realized that this place just wasn't for us, we both left and I've never seen her since. I obviously wouldn't have died without her, but I definitely wouldn't have improved so much as a swimmer and just as a person.

21. What do we know about the author's swimming coach?

A. She seems impatient with her students. B. She is quite popular among her students.

C. She left a good first impression on the author.

D. She was an Olympian and is known for her freestyle swimming.

22. The underlined word "grueling" in Paragraph 5 probably means .

A. boring B. exhausting C.enjoyable D. meaningful

23. How did the author survive her training days?

A. By practicing really hard. B. With the encouragement of her coach

C. By chatting with her teammates. D. With the help of a new friend.

　　Chimpanzees do have stronger muscles than us - but they are not nearly as powerful as many people think.

　　"There's this idea out there that chimpanzees are superhuman strong, "says Matthew O'Neill at the University of Arizona in Phoenix. Yet his team's experiments and computer models show that a chimpanzee muscle is only about a third stronger than a human one of the same size.

　　This result matches well with the few tests that have been done, which suggest that when it comes to pulling and jumping, chimps are about 1.5 times as strong as humans

relative to their body mass. But because they are lighter than the average person, humans can actually outperform them in absolute terms,says O'Neill.

　　　His findings suggest that other apes have similar muscle strength to chimpanzees. "Humans are the odd ones, " he says.

　　O'Neill's team has been studying the evolution of upright walking. To create an accurate computer model of how chimps walk, the researchers needed to find out whether their muscles really are much stronger. So they removed small samples of

leg muscle from three chimps and measured the strength of individual fibers(纤维).

　　The same procedure is used to study human muscles. Comparing the results with the many studies on those showed that, contrary to the claims of several other studies, there is nothing special about chimp muscle. "Chimpanzee muscle is really no different than human muscle in terms of the force that individual fibers use, says O'Neill.

　　So why, on a pound-for-pound basis, are chimps slightly stronger than humans? The team went on to look at the muscle of chimps that had died of natural causes, which showed that two-thirds of their muscle is made of fast-twitch fibers, whereas more than half of human fibers are slow-twitch. Fast-twitch fibers are more powerful, but use more energy and become tired faster.

　　Another factor, O'Neill found, is that chimps have longer fibers on average which also improves their strength.

　　This adds to the evidence that walking uses far more energy for chimps than for people. The results fit well with the idea that early humans evolved to walk or run

long distances. It seems that we gave up some strength for greater endurance(耐力).

24. What does O'Neill mean when he says"Humans are the odd ones"(in para4)?

A. Humans are better at jumping and pulling things than chimps

B. There is nothing special about human muscles

C. Humans are heavier and stronger than chimpanzees.

D. Humans' muscle strength is different from that of apes

25. What contributes a lot to the strength of chimp muscles?

A. The evolution of upright walking

B. The slow-twitch fibers in their muscles

C. The fast-twitch fibers in their muscles.

D. Most of their muscles being made of short fibers

26. We can infer from the text that .

A, short fibers provide more energy for the muscle

B. human muscles are more suited to long distance running

C. early humans needed much more energy than chimps

D slow-twitch muscle fibers help chimps survive in the wild