单选题 Color is very important to most animals for it helps them to get along in the world. Color (21) to make an animal difficult for its enemies to (22) . Many animals match their (23) so well that as long as they do not move no one is (24) to see them. You probably have often "jumped" a rabbit. If you (25) , you know how the rab- bit sits perfectly still (26) you are just a few feet away. You (27) see the rabbit till it runs for its (28) matches very closely the place where it is (29) . Many times you may have walked past a rabbit (30) didn't run and you never knew it was there at all.
One of the most usual color schemes that helps animals to keep (31) being seen, is a dark back and light underpants. If an animal is the same color all (32) , there is always a dark shadow along the animal's belly (腹部). (33) an enemy couldn't see the animal he could see this dark shadow. The shadow makes the animal (34) out to view. But if the belly is (35) than the rest of the animal, the shadow will not be noticed.

单选题 A. helps B. contributes C. tries D. manages

【正确答案】 A

【答案解析】[解析] A项helps意为“帮忙，帮助”，符合题意。B项contributes意为“贡献”；C 项tries意为“试图”；D项manages意为“设法”。

单选题 A. watch B. see C. catch D. kill

【正确答案】 B

【答案解析】[解析] 本句意为：“有了颜色的帮助，动物的天敌就很难看到它。”watch意为“观看，注视”；see意为“看见，了解”；catch意为“抓住”；kill意为“杀死”。B项符合题意。

单选题 A. conditions B. surroundings C. enemies D. bodies

【正确答案】 B

【答案解析】[解析] B项surroundings意为“环境”，符合题意，如：railway surroundings铁路周围环境。A项conditions意为“条件”；C项enemies意为“敌人”；D项bodies意为“身体”。

单选题 A. enable B. hardly C. likely D. possible

【正确答案】 C

【答案解析】[解析] 本句可译为：“只要他们不动，没人能看到他们。”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；D项possible常用形式为It’s possible…。

单选题 A. do not B. had not C. did D. have

【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项均无法使句子正确。

单选题 A. where B. there C. while D. until

单选题 A. sometimes B. occasionally C. seldom D. often

【正确答案】 C

【答案解析】[解析] C项seldom意为“很少，不常”，有否定含义，与题意相符。B项occasionally意为“偶尔”，A、B、D项三个频度副词均无否定含义。

单选题 A. surface B. coat C. shape D. appearance

【正确答案】 B

【答案解析】[解析] B项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。

单选题 A. sitting B. matching C. running D. jumping

单选题 A. you B. that C. it D. which

单选题 A. out of B. on C. from D. off

单选题 A. alone B. together C. over D. right

【正确答案】 C

【答案解析】[解析] 该句意为“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。

单选题 A. Even if B. Unless C. However D. As long as

单选题 A. stand B. stretch C. push D. bring

【正确答案】 A

【答案解析】[解析] stand out意为“显眼，突出”；stretch out意为“伸手，开始大踏步走”； push out意为“把……推出去”；bring out意为“使显示，出版，产生”。只有A项正确。