据报道,我国学生近视率居世界第一。造成这一现象的原因是多方面的, 请你以 "Why are more and more children getting short-sighted?" 为题, 写一篇英语短文。
内容主要包括：
1. 造成学生近视的原因；
2. 如何保护视力？
注意: 1.词数120左右；
2.可以适当增加细节, 以使行文连贯；
3.短文的开头已经写好, 不计入总词数。
参考词汇: 近视率 rate of myopia
Why are more and more children getting short-sighted?
It is reported that the rate of myopia of Chinese students is ranked as the highest in the world _______________________________________________________________________
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