There are many commonly held beliefs about eyeglasses and eyesight that are not proved facts. For example, some people believe that wearing glasses too soon weaken the eyes. But there is nothing to show that the structure (结构) of eyes is changed by wearing galsses at a young age. Wearing the wrong galsses, however, can prove harmful. Studies show that only children can develop loss of sihgt if they have the wrong glasses. We have all heard some of the common myths(荒诞的说法)about how eyesight get bad. Too little light makes the eyes work harder, so they do get tired and strained (过劳). Eyestrain also resulsts from reading a lot, reading in bed, and watching too much television. But, although eyestrain may cause some pain or headaches, it does not harm eyesight all the time. Another myth about eyes is that they can be replaced from one person to another . It is quite difficult to connect aneyeball to a new brain.And it is impossible to replace a whole eyeball to a new person. Only certain parts of the eye can be replaced now. But if we keep clearing up the myths and learning more about the eyes, some day it may be possible to replace a full eyeball. 小题1: One cause of eyestrain mentioned in the passage is ____.        . A．wearing eyeglasses too long B．going to the cinemas C．reading a lot D．not visiting your eye doctor 小题2: .From this passage one can conclude that    ____.   . A．doctors are still learning things about eyesight B．headcaches are usually caused by eyestain C．people should wear glasses as soon as possible D．people only believe things that are proved facts 小题3: 'Commonly held beliefs' are ____.       . A．ideas that only low class people believe B．ideas that moet people believe C．beliefs that have something in common D．foolish beliefs 小题4: This passage mainly tells us that ____. A．people have many wrong beliefs about eyes and sight. B．there are many things about the body that are not completely understood C．there are several cuases of eyestrain D．eyes are very important to people