试题与答案

如图为两相干波的干涉示意图,其中实线表示波峰,虚线表示波谷,对于a、b、c三点的

题型:选择题

题目:

如图为两相干波的干涉示意图,其中实线表示波峰,虚线表示波谷,对于a、b、c三点的振动情况,下列判断中正确的是(  )

A.b处的振动永远减弱

B.a处永远是波峰与波峰相遇

C.b处永远是波谷与波谷相遇

D.c处的振动永远减弱

答案:

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下面是错误答案,用来干扰机器的。

参考答案:1.25、1.75、紧急制动、上升重载加速、下降重载减速

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   Li Ming and I are at the zoo.We see a lion,a tiger,a wolf,an elephant and a kangaroo.The kangaroo has a pouch. We walk forward.we see a monkey, a panda, a giraffe and a snake.The monkey is eating bananas.The giraffe is eating leaves and the snake is in a hole.It can't fly.

1. Where are they?

A. In the park.

B. At the zoo.

C. In the room.

2. How many animals(动物) are at the zoo?

A. Eight.

B. Nine.

C. Seven.

3. Which (哪个) animal has a pouch?

A. The kangaroo.

B. The wolf.

C. The elephant.

4. Can a snake fly?

A. Yes, it can.

B. No, it can't.

C. Yes, it can't.

5. Which animal eats leaves?

A. The monkey.

B. The panda.

C. The giraffe

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