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问题 单项选择题

离心式水泵正常启动后，闸阀由关闭逐渐到全开，其压力表指数是（）。

A.由零位逐渐上升到初始压力

B.由初始压力逐渐下降到一定压力

C.由初始压力逐渐下降到零位

D.基本保持不变的

答案

参考答案：B

完形填空

根据短文内容及所给首字母，填写所缺单词，每空一词

I think April Fool’s Day is a very unusual festival. On April Fool’s Day, you can play jokes on others. You cannot believe(相信) everything you hear on A  1 1st. Even some main newspapers will put fake (假的) articles into their papers to fool people. I hear a story about a London newspaper. There is an article on it. It says that some r  2 will do bad things in England bank on April Fool’s Day. This m 3   many people surprised and the l  4  police are very busy. It can be fun sometimes to play tricks, b   5  you have to be careful not to go too far.

O  6  April Fool’s Day this year, I c  7 my mother from my school. I tell her that I f  8 in all of my exams. She feels so bad that she starts to cry. I feel really s  9  about making her sad and try to tell her it is just a joke. April Fool’s Day jokes can be funny, but you should be c  10  not to hurt people’s feelings.
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选择题
如图所示，AB是一质量为m的均匀细直杆，A端靠在光滑的竖直墙壁上，B端置于水平地面上，杆身与竖直方向夹角为θ，杆与地面的摩擦系数为μ，保持平衡，则此时杆与地面的摩擦力为（　　）

A．mgtgθ

B．mgsinθ

C．μmg

D．μmg
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