某列机械波在MN直线上传播，该直线上相距3m的P、Q两质点，其振动

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问题不定项选择

某列机械波在MN直线上传播，该直线上相距3m的P、Q两质点，其振动图象如图所示，则

[ ]

A、该机械波的频率为2.5Hz

B、该机械波的传播方向一定是从P到Q

C、该机械波的波长可能为4m

D、该机械波传播的速度可能为15m/s

答案

阅读理解

看图，根据对话打“√”或“×”判断对错。

Liu: Excuse me. Where is the Zhong bai Supermarket, please?

Policeman: It's west of the hospital.

Liu: Is it far from here?

Policeman: Yes.

Liu: How can I get there?

Policeman: First, turn left and take the No. 16 bus at the bus stop. Next, get off at the hospital. Then, cross

(穿过) the street. You'll be in front of the Supermarket.

Liu: Thank you.

Policeman: You're welcome.

( ) 1. The post office is next to the supermarket.

( ) 2. The supermarket is west of the hospital.

( ) 3. Liu Yun goes to the supermarket on foot.

( ) 4. Liu Yun asks a policeman for help.

单项选择题

新生儿败血症最多见的感染途径（）

A.产道感染

B.脐部感染

C.暖箱

D.雾化器

E.宫内感染