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问题 选择题

下列家用电器工作时，电能主要转化为机械能的是（　　）

A．电冰箱

B．电风扇

C．电烙铁

D．微波炉

答案

电流做功的过程，实际上就是个能量转化的过程，从电能转化成其它形式的能；在常见的家用电器中，电烙铁是将电能转化为内能的；电风扇是把电能转化为机械能；微波炉将电能转化为光能；电冰箱消耗电能，实现热量由低温物体向高温物体的传递；

故选B．

阅读理解

阅读理解。

     This is a picture of Mr. Li's family. The man in the middle is Mr. Li. The woman is Mr. Li's wife. They have two sons. The child behind Mr. Li is Li Lei. He's thirteen. The other in front of Mrs. Li is Li Ming. He is eleven. Li Lei and Li Ming are in the same school, but not in the same grade. Li Lei is in Grade Two. Li Ming is in Grade One. They are good students.

1. There are _______ people in the picture.

A. three

B. four

C. five

D. six

2. LiLei and Li Ming ______ in the same grade.

A. is

B. isn't

C. are

D. aren't

3. Mr. and Mrs. Li have _______.

A. one boy, one girl

B. two children

C. two girls

D. one boy

4. Li Ming is ________ brother.

A. Mr. Li's B. Mrs. Li's

C. Li Lei's

D. we don't know.

5. How old are Li Lei and Li Ming? They're _____.

A. eleven and thirteen

B. eleven and twelve

C. twelve and eleven

D. thirteen and eleven

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单项选择题

气管切开术后出现广泛皮下气肿，最简单的处理方法是（）。

A.抽吸气体

B.松解伤口缝线

C.更换气管套管

D.让其自行吸收

E.以上都不是
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