（三）
All mammals(哺乳动物) need sleep. But the amount of sleep they need is different. Children need21．(many) sleep than grown-ups. A new born baby sleeps 17 to 18 hours a day. Grown-ups need between 6 and 9 hours of sleep a night.
Though22．(science) do not know for sure why you sleep, they do have some ideas. Safety could be23．most important reason for sleep. People and other animals might sleep because it keeps them safe at night. Things go wrong if you do not get enough sleep.
24．is hard to think and work unless you get plenty25．sleep.
In the past twenty years, people26．(learn) a lot about what happens when you lie down to sleep. Sometimes your eyeballs move back and forth very fast. This kind of sleep is called REM,27．means rapid eye movement. One28．(interest) fact about this kind of sleep is that dreaming occurs during REM.
If you have trouble29．(fall) asleep, there is an old suggestion that you breathe very30．(slow). Others believe that drinking warm milk will help make you drowsy.
参考答案与解析（三）
21．more
22．scientists
23．the
24．It
25．of
26．have learned
27．which
28．interesting
29．falling
30．slowly
【分析】
这是一篇说明文。短文介绍了睡眠的时间，原因，以及如何应对难以入眠的建议
21．
考查形容词比较级。句意：儿童比成人需要更多的睡眠。根据“than”可知，空处填形容词比较级。故填more。
22．
考查名词。句意：尽管科学家们还不能确定你为什么要睡觉，但他们确实有一些想法。根据句意、下文的“they”以及谓语“do not”可知，空处填名词复数scientists，故填scientists。
23．
考查冠词。句意：安全可能是睡眠最重要的原因。根据句意表示“最重要的原因”，最高级前为定冠词the，故填the。
24．
考查代词it。句意：除非你有充足的睡眠，否则很难思考和工作。It is+形容词+to do sth , it做形式主语。故填It。
25．
考查介词。句意：除非你有充足的睡眠，否则很难思考和工作。plenty of“许多，大量”为固定短语。 故填of。
26．
考查时态。句意：在过去的二十年里，人们已经了解了很多当你躺下睡觉时会发生什么。根据“In the past twenty years ”可知本句为现在完成时，主语为people。故填have learned。
27．
考查非限制性定语从句。句意：这种睡眠被称为REM，意思是快速眼球运动。REM为先行词，作非限制性定语从句的主语，关系代词为which。 故填which。
28．
考查形容词。句意：于这种睡眠的一个有趣的事实是，做梦发生在REM期间。以ing结尾形容词常修饰表示物的名词，本句修饰的是fact，故填interesting。
29．
考查动名词。句意：如果你难以入睡，有一个古老的建议，那就是放慢呼吸。have trouble (in) doing sth. , 结合所给出的词，故填falling。
30．
考查副词。句意：如果你难以入睡，有一个古老的建议，那就是放慢呼吸。副词slowly修饰动词breathe, 故填slowly。
All mammals(哺乳动物) need sleep. But the amount of sleep they need is different. Children need21．(many) sleep than grown-ups. A new born baby sleeps 17 to 18 hours a day. Grown-ups need between 6 and 9 hours of sleep a night.
Though22．(science) do not know for sure why you sleep, they do have some ideas. Safety could be23．most important reason for sleep. People and other animals might sleep because it keeps them safe at night. Things go wrong if you do not get enough sleep.
24．is hard to think and work unless you get plenty25．sleep.
In the past twenty years, people26．(learn) a lot about what happens when you lie down to sleep. Sometimes your eyeballs move back and forth very fast. This kind of sleep is called REM,27．means rapid eye movement. One28．(interest) fact about this kind of sleep is that dreaming occurs during REM.
If you have trouble29．(fall) asleep, there is an old suggestion that you breathe very30．(slow). Others believe that drinking warm milk will help make you drowsy.
参考答案与解析（三）
21．more
22．scientists
23．the
24．It
25．of
26．have learned
27．which
28．interesting
29．falling
30．slowly
【分析】
这是一篇说明文。短文介绍了睡眠的时间，原因，以及如何应对难以入眠的建议
21．
考查形容词比较级。句意：儿童比成人需要更多的睡眠。根据“than”可知，空处填形容词比较级。故填more。
22．
考查名词。句意：尽管科学家们还不能确定你为什么要睡觉，但他们确实有一些想法。根据句意、下文的“they”以及谓语“do not”可知，空处填名词复数scientists，故填scientists。
23．
考查冠词。句意：安全可能是睡眠最重要的原因。根据句意表示“最重要的原因”，最高级前为定冠词the，故填the。
24．
考查代词it。句意：除非你有充足的睡眠，否则很难思考和工作。It is+形容词+to do sth , it做形式主语。故填It。
25．
考查介词。句意：除非你有充足的睡眠，否则很难思考和工作。plenty of“许多，大量”为固定短语。 故填of。
26．
考查时态。句意：在过去的二十年里，人们已经了解了很多当你躺下睡觉时会发生什么。根据“In the past twenty years ”可知本句为现在完成时，主语为people。故填have learned。
27．
考查非限制性定语从句。句意：这种睡眠被称为REM，意思是快速眼球运动。REM为先行词，作非限制性定语从句的主语，关系代词为which。 故填which。
28．
考查形容词。句意：于这种睡眠的一个有趣的事实是，做梦发生在REM期间。以ing结尾形容词常修饰表示物的名词，本句修饰的是fact，故填interesting。
29．
考查动名词。句意：如果你难以入睡，有一个古老的建议，那就是放慢呼吸。have trouble (in) doing sth. , 结合所给出的词，故填falling。
30．
考查副词。句意：如果你难以入睡，有一个古老的建议，那就是放慢呼吸。副词slowly修饰动词breathe, 故填slowly。
