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问题 选择题

MN为半圆形玻璃砖截面的直径，OO′为过圆心且垂直于MN的直线。两束可见单色光a、b与OO′的距离均为d，从空气垂直MN射入玻璃砖中，光路如图所示。由此可知

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A．玻璃对a光的折射率比对b光的小

B．a光的频率比b光的小

C．相同条件下a光的干涉条纹间距比b光的大

D．若b光照射某金属能发生光电效应，则a光照射该金属也能发生光电效应

答案

答案：D

填空题

根据句意和首字母填写单词。

1. There are all kinds of animals in the z_____.

2. I had a glass of m_____ and some bread this morning.

3. We asked the teacher to sing an English s_____ for us.

4. Mother cut the birthday c_____ with a knife at the party.

5. When spring comes, the sky is b_____ and the sun is bright.

6. —What's your favorite s_____?

    —Volleyball.

7. Students can b_____ books from the school library.

8. You must be q_____. The baby is asleep.

9.  Ninety-nine and one is one h_____.

10. He stayed in the hospital for six weeks with a s_____ illness.

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单项选择题

“三防”不包括下列哪一项防护？（）

A.核武器防护

B.化学武器防护

C.生物武器防护

D.轻武器防护
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