One cause of eyestrain mentioned in the passage is______.

For this part, you are supposed to write a composition of about 100 -120 words based on the following situation. Remember to write it clearly.你校学生会将为来访的美国朋友举办一个晚会，要在学校广播中宣布此事，并欢迎大家参加。为使美国朋友听瞳，请你用英语写一篇广播通知。要点如下：(1)宗旨：欢迎来访的美国朋友；(2)组织者：学生会；(3)时间：8月13日(星期六)晚7：30；(4)地点：主楼屋顶花园；(5)活动内容：音乐、跳舞、唱歌、游戏、交换小礼品(请包装好、签名并在包装外面写上祝愿词)。 注意：应包括以上要点，但不要逐字翻译，要组织成一篇通顺连贯的短文；开头语已为你写好。 生词：交换礼品——to exchange gifts；学生会——the Students’UnionMay I have your attention, please? I have an announcement to make.______

Sleeping pills should never be taken except when suggested by【C15】______

the avoidance of late eating and【C12】______are all helpful to sound sleep

Such factors are largely within the【C13】______of any person.

A bath at【C14】______, neither hot nor cold but of body temperature,

probably gives the body【C10】______complete relaxation.  

【C9】______a person can keep himself warm,

Out-of-door【C11】______, a good habit of regular drinking

It is not【C8】______reason for some people to insist that

Fresh air is【C7】______to sound sleep(酣睡).