题干

两栖动物在生物圈中经历了由盛到衰的过程(如表),其主要的自身原因是(    )

距今大概的年数

两栖动物发展状况

环境条件

3.45 亿~2.25 亿年

种类多,两栖动物繁盛

气候温暖潮湿,水域密布

2.25 亿年至今

种类减少,两栖动物走向衰退

气候干燥,水域减少

A:两栖动物的繁殖能力差

B:两栖动物的神经系统不发达

C:两栖动物的生活影响了环境

D:两栖动物的生殖和幼体发育必须在水中进行

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答案(点此获取答案解析)

D

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完形填空

    Are you a man or a mouse? When people ask this question they want to know whether you think you are a brave person or a coward(懦夫). But you will never really know the answer to this question 1you are tested in real life. Some people 2they are brave but when they come face to face with real danger, they act like cowards. Others consider themselves as cowards, but when they meet danger, they act like3.

    Lenny had always thought of himself as a 4person. He got worried before examinations. He worried about his job and his health. All he wanted in life was to be safe and healthy. Then, on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to see what was happening. He saw a woman in the ice-cold water. Lenny did not feel afraid. He kept very 5and did a very adventurous thing. He jumped into Potomac, swam to the woman, and kept her head above the water. Seventy-eight people died that day. Thanks to Lenny, it was not 6.

    When you are in a very dangerous situation and feel afraid, the body automatically (自动地) produces a chemical in the blood. This chemical is called adrenalin(肾上激素). With adrenalin in the blood system, you actually feel stronger and stronger and are ready to fight or7 However, when you are absolutely terrified, the body can produce too much adrenalin. When this 8 the muscles become very hard and you find you can't move at all. You are paralyzed(使无能为力) with fear. This is9 when we are very frightened, we sometimes say we are “petrified”. This word comes from a Greek word “petros”, which means “stone”. We are10 frightened that we become stonelike.