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问题 选择题

一人握住竖直竹杆往上爬，则下列说法中不正确的是（　　）

A．人所受的摩擦力是静摩擦力

B．人握旗杆所用的力越大，所受的摩擦力也越大

C．人受的摩擦力的方向竖直向上

D．人受的摩擦力的摩擦力大小等于人所受的重力大小

答案

A、C、人握住杆匀速上爬时，人相对于杆有向下滑的趋势，受到杆的静摩擦力方向向上．故AC正确；

    B、人竖直方向受到重力和摩擦力，由平衡条件分析得知，人受的摩擦力等于人的重力，保持不变，所以人握杆用力越大，并不会使人受的摩擦力增大．故B错误、D正确；

本题选择不正确的，故选B．

改错题

短文改错（共10小题; 每小题1分，满分10分）

Good morning, ladies and gentlemen.

Some of us are having problems about our parents, as they often look into our school bags or read our diaries. I fully understand why we are comfortable about it, but it is no need to feel too sad. Our parents are checking in our bags or diaries to make sure we’re not getting into troubles. They have probable heard of some horrible stories about another kids and think we might do the same. Or perhaps they just want to connect with us and are doing it all wrong. My suggestion is: tell them we wanted them to trust us as much as we’d like to trust them. If you don’t think you can talk to them, write them a letter and leave it lie around—they are bound to read it.

Thank you!
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单项选择题

淋巴细胞是免疫活性细胞，以下哪种细胞不属于其中（）

A.B细胞

B.T细胞

C.K细胞

D.NK细胞

E.单核巨噬细胞
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