单选题 All 21 things must fight to stay alive. They have to feed on something and at the same time avoid being 22 . Therefore they have to solve this big problem of staying alive in their own way. The danger of being eaten in the sea is great. Those plants and animals that do survive usually 23 very fast and in great numbers.
24 sea animals have defensive devices which help them to survive. The jelly fish have 25 tentacles (触角) which are used for attack and defense. Another method of 26 which sea plants and animals use is disguise. They usually have the same 27 as their surroundings.
In order to stay alive, animals need to have good senses. Fishes have sharp eyes. Almost all animals are sensitive to 28 . Fishes judge movements in the water by 29 of their lines. Fishes and other sea animals can hear well and many of them can 30 different types of warning sound.
【正确答案】 A
【答案解析】[解析] 根据四个单词的区别，“生物”应为living things。
【正确答案】 D
【答案解析】[解析] 固定搭配：avoid doing sth.意为“避免做某事”。
【正确答案】 B
【答案解析】[解析] 根据上下文意思，此处指动植物“再生”。
【正确答案】 C
【答案解析】[解析] 由谓语动词形式可知，certain指“某些”。
【正确答案】 C
【答案解析】[解析] 根据下文得知此处指“有毒的”触角。
【正确答案】 B
【答案解析】[解析] 指海底动植物生存的另一种方法。
【正确答案】 A
【答案解析】[解析] 这些动物有与周围环境相同的颜色，即保护色。
【正确答案】 C
【答案解析】[解析] 所有动物对触摸很敏感。
【正确答案】 B
【答案解析】[解析] 固定搭配，by means of 意为“用……的方法”。
【正确答案】 A
【答案解析】[解析] 固定搭配，make sound/noise意为“弄出声音”。