Enough sleep is important to health.The amount of sleep needed depend on the age of the person and the conditions in (which ) sleep take place.The young may need more sleep than the old,but usually eight hours are enough for the health of grown-ups.Some can do with ( even) less than this amount,but others may need more.Every person knows his own need.( It) is then a matter of good judgement to satisfy his need. Sleep (must) always be enough to make one bring back his (strength)名词(strong的正确形式) and get ready for a day's work. 第1空：是一个状语从句，因为前面已经有一个表示状态的介词了，所以直接填一个which引导从句便可，which其实是代conditin的。第2空：我不太确定，就填了个副词，参考下吧。第3空：这个是一个固定结构：It+is/was+表语+to什么什么。意思是做什么什么是怎样怎样的。第4空：根据句子判断这里应该是一个情态动词，所以填个意思最贴切的，其实我一直觉得should可以，但是我老师一直不让我这样用。。。。。第5空：单词的功底了。参考文献：自己和隔壁那个圣人的。

Enough sleep is important to health.The amount of sleep needed depend on the age of the person and the conditions in (which ) sleep take place.The young may need more sleep than the old,but usually eight hours are enough for the health of grown-ups.Some can do with ( in) less than this amount,but others may need more.Every person knows his own need.( It) is then a matter of good judgement to satisfy his need. Sleep (must ) always be enough to make one bring back his (strength)名词(strong的正确形式) and get ready for a day's work. 参考文献：个人观点