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问题 问答题 简答题

皮带机头部主动滚筒为什么采用人字形胶面滚筒。若胶面磨损严重时，对皮带有什么危害。

答案

参考答案：

采用人字形胶面滚筒，增大皮带与滚筒的摩擦系数，隔断水膜，防止皮带打滑。胶面磨损摩擦系数降低，皮带打滑。

阅读理解

阅读理解。

     This is Jim's room. It's small but very nice. There is (有) a chair, a desk and a bed in the room. A

computer and some books are on the desk. The bed is next to the desk. Under the desk, there is a

baseball. His computer game is under the bed. There is a photo of his family on the wall(墙). He likes his

room.

1. There is              in the room.  

A. a desk        

B. two desks      

C. three chairs

2.              are on the desk.

A. A book and a computer  

B. A computer and some books

C. Some books and some computers

3. There is               under the desk.  

A. a chair  

B. a computer game    

C. a baseball

4. There is               on the wall.

A. a photo of his classmates    

B. a photo of his teachers    

C. a photo of his family

5. The room is              .  

A. small      

B. nice        

C. small and nice

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单项选择题

蛲虫病的预防措施不包括

A．在集体儿童机构，开展普查
B．进行卫生宣教工作
C．每年预防性口服灭虫药物
D．培养良好的卫生习惯
E．集体儿童机构勤用湿扫法打扫室内
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