单选题 Color is very important to most animals for it helps them to get along in the world. Color (61) to make an animal difficult for its enemies to (62) . Many animals match their (63) so well that as long'as they do not move no one is (64) to see them. You probably have often "jumped" a rabbit. If you (65) , you know how the rabbit sits perfectly still (66) you are just a few feet away. You (67) see the rabbit till it runs for its (68) matches very closely the place where it is (69) . Many times you may have walked past a rabbit (70) didn't' run and you never knew it was there at all.
One of the most usual color schemes that helps animals to keep (71) being seen, is a dark back and light underpants, if an animal is the same color all (72) , there is always a dark shadow along the animal's belly (腹部). (73) an enemy couldn't see the animal he could see this dark shadow. The shadow makes the animal (74) out to view. But if the belly is (75) than the rest of the animal, the shadow will not be noticed.

【正确答案】 A
【答案解析】[解析] A项helps意为“帮忙，帮助”，符合题意。contributes意为“贡献”；tries意为“试图”；manages意为“设法”。
【正确答案】 B
【答案解析】[解析] watch是“观看，注视”；see是“看见，了解”；catch是“抓住”；kill是“杀死”。B项符合题意。
【正确答案】 B
【答案解析】[解析] surroundings意为“环境”，符合题意，如：railway surround lags铁路周围环境。conditions意为“条件”。enemies意为“敌人”。
【正确答案】 C
【答案解析】[解析] 谓语不完整，缺少表语部分，A项可排除；B项hardly无法使意思成立；possible常用形式为It's possible…。
【正确答案】 D
【答案解析】[解析] 此处为省略句，根据前一句You probably have often“jumped”a rabbit，完整的句子应为：If you have often jumped a rabbit...。A、B、C三项均无法使句子正确。
【正确答案】 D
【答案解析】[解析] 句子中缺少引导状语的连词，until意为“直到……之时”，故而A、B、C三项均不正确。
【正确答案】 C
【答案解析】[解析] secom意为“很少，不常”，有否定含义，符合题意。occasionally意为“偶尔”，A、B、D三项是三个频度副词，均无否定含义。
【正确答案】 B
【答案解析】[解析] coat意为“覆盖物(动物的毛)”，使句子意思完整，符合题意。A项surface意为“表面”；C项shape意为“形状”；D项appearance意为“面貌”均不符合题意。
【正确答案】 A
【答案解析】[解析] 根据前句：You know how the rabbit sits perfectly still…，所以A项正确。matching意为“匹配”。
【正确答案】 B
【答案解析】[解析] 此处缺少定语从句的关系代词，只有that可指代无生命及有生命的东西。
【正确答案】 C
【答案解析】[解析] keep…from…有“免于”之意。
【正确答案】 C
【答案解析】[解析] 该句译为“遍及……每一部分，浑身(all over)”。all alone意为“独自”；all together意为“总共”；all right意为“可以”，均不正确。
【正确答案】 A
【答案解析】[解析] Even if意为“即使”，可引导让步状语从句，此处前后句子有让步的关系，故A项正确。
【正确答案】 A
【答案解析】[解析] stand out意为“显眼，突出”。stretch out意为“直躺”；push out意为“大量推出”；bring out意为“使显示，出版，产生”。只有A项正确。
【正确答案】 D
【答案解析】[解析] 这里表示颜色的深浅，而由上文，腹部颜色浅则较难被注意到，故而D项lighter“比……浅”符合题意。