content: Directions: There are 20 blanks in the following passage, and for each blank there are 4 choices marked A, B, C and D at the end of the passage.You should choose ONE answer that best fit into the passage.Then blacken the corresponding letter on the Answer Sheet\nEnough sleep is important to health.The amount of sleep 56 depends on the age of the person and the conditions in which sleep 57 .The young may need more sleep than the old.but 58_ eight hours are enough for the 59 of grown-ups.Some can 60 with less than this amount but 61 may need more.Every person knows his own 62 .It is then a matter of how to 63 it.Sleep should always be 64 to make one relaxed and ready for 65 work.\nFresh air is 66 to sound sleep.It is not 67 reason for some people to 68 that it is practical to sleep in the open air. 69 a person can keep himself warm, 70 sleeping probably gives the body 71 complete relaxation.\nAbility to sleep is largely a 72 .Out-of-door 73 , a good habit of regular 74, the avoidance (避免) of late eating, and 78 are all helpful to sound sleep. , ——————are enough for the 59 of grown-ups
选项：

A:Health
B:heads
C:night
D:work