问题
填空题
为了检查一块木板是否笔直，可以闭上一只眼睛，用另一只眼睛沿木板棱的方向看过去，这利用了什么原理？
答案
答：这利用了光的直线传播的原理；
由于光在同一均匀介质中是沿直线传播的，如果一块板子有弯曲，凸起部分就会挡住前端的光线，看不到木板的前端了．
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为了检查一块木板是否笔直，可以闭上一只眼睛，用另一只眼睛沿木板棱的方向看过去，这利用了什么原理？
答：这利用了光的直线传播的原理；
由于光在同一均匀介质中是沿直线传播的，如果一块板子有弯曲，凸起部分就会挡住前端的光线，看不到木板的前端了．
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| There is a zoo in our city. The zoo is very big. It has all kinds of 1 . You can see the tigers, elephants, monkeys, pandas, dolphins (海豚) and many 2 in it. 3 people visit it every day. Today is Sunday. Jim and his classmates 4 no classes. They are at the zoo. Jim likes pandas. They 5 from Sichuan. Tom 6 tigers are lovely, 7 Lily doesn't think so. She thinks 8 are dangerous (危险的). She asks Tom 9 the dolphins. She thinks dolphins are 10 , and they can dance very well. Jim and his classmates have a good time at the zoo. | ||||
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