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问题 单项选择题

用水进行反冲洗，把滤料颗粒冲成悬浮状态后，由滤料间高速水流所产生的（）把悬浮物冲下来，并用水反冲洗。

A.惯性

B.粘着力

C.推力

D.剪切力

答案

参考答案：D

选择题
Look and choose. (选出与图画内容相符的句子)
( )1. A. Don't swim here.
           B. I went swimming last week.
           C. He likes swimming.
(     )2. A.Yesterday was snowy.     
           B. Yesterday was rainy.    
           C. Yesterday was cloudy.
( )3. A. I often do the dishes after supper.
           B. I often practice the piano after supper at home.
           C. I often wash clothes after supper.		                                                
( )4. A.Tony has a cup of coffee.     
           B. Tony is wearing his sunglasses.
           C. Tony likes eating ice-creams.
( )5. A. The tiger has a short tail.     
           B. My mother has a big dog.     
           C. My grandpa is feeding his cat.
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单项选择题

为使下列代码正常运行，应该在下面线处填入的选项是______。
ObjectlnputStream In=
new______(new FileInputStream("employee. doc"));
Employee [] newstaff=(Employee[]) in. readobject ();
In.close();

A．Reader
B．InputStream
C．Objectlnput
D．ObjectlnputStream
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