一列简谐横波沿x轴正向传播,传到M点时波形如图所示,再经0.6s,N点开始振动,

题型:选择题

问题:

一列简谐横波沿x轴正向传播,传到M点时波形如图所示,再经0.6s,N点开始振动,则该波的振幅A和频率f为(  )

A.A=1m,f=5Hz

B.A=0.5m,f=5Hz

C.A=1m,f=2.5Hz

D.A=0.5m,f=2.5Hz

考点:波长、频率和波速
题型:选择题

阅读理解。

      

     Which animal do you think is "the king of the animals", the elephant, the lion or the tiger? They are all

 large and strong. But I think the tiger is "the king of the animals". If you watch carefully, you can find some

  black lines on the tiger's forehead (前额). The lines look like the Chinese word "WANG". The word

  means "the king of the world" in Chinese.

     Most of the tigers come from China and India. Tigers are dangerous animals. They look scary (吓人

 的). They like eating meat. They have yellow fur with black lines. They usually weigh about 200 to 300kg.

  Tigers can run fast. They run at a speed of 20 meters per second.

     Some people think they are dangerous. But they don't know tigers are in danger now. There are only

  20 to 30 wild South China Tigers in China and less than 300 in the world. Lots of people kill them for

 their fur. We should take action to protect them.

1. Which animal does the writer think is "the king of the animals" ?

    A. The elephant.              

    B. The lion.

    C. The tiger.                  

    D. The lion and the tiger.

2. Some black lines on the tiger's forehead look like _____.

    A.王     

    B.汪      

    C. 主      

    D. 丰

3. Which of the following is NOT true according to the passage?

     A. Tigers like eating meat.

     B. All of the tigers come from China.

     C. Tigers usually weigh about 200 to 300 kg.

     D. Tigers can run at a speed of 20 meters per second.

4. How many wild South China Tigers are there in China?

    A. There are less than 20.

    B. There are only 20 to 30.

    C. There are less than 200.

    D. There are less than 300.

5. Why do you think the tigers are in danger?

    A. Because the tigers couldn't find enough food to eat.

    B. Because lots of people kill them for their safety.

    C. Because lots of people think they are dangerous.

    D. Because lots of people kill them for their fur.

题型:选择题

假想用一个剖切平面将零件的某部分剖切开来,仅画出这部分的形状,称为()。

A、剖视图

B、剖面图

C、局部剖视图

D、全剖视图

题型:选择题

约伯的三个朋友包括:()

A、提幔人以利法;

B、布西人以利户;

C、提斯比人以利亚。

题型:选择题

关于卵巢肿瘤蒂扭转的处理,下列哪项正确()

A.剖腹后立即缓解扭转

B.剖腹后立即行肿瘤切除术

C.缓解扭转后行肿瘤切除术

D.先将蒂部夹住,复位后切除

E.缓解扭转后行患侧附件切除术

题型:选择题

部件通用化

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