试题与答案

某动车组列车以平均速度v从甲地开到乙地所需的时间为t,该列车以速度v0从甲地出发匀速

题型:单项选择题

题目:

某动车组列车以平均速度v从甲地开到乙地所需的时间为t,该列车以速度v0从甲地出发匀速前进,途中接到紧急停车命令紧急刹车,列车停车后又立即匀加速到v0继续匀速前进,从开始刹车至加速到v0的时间是t0(列车刹车过程与加速过程中的加速度大小相等),若列车仍要在t时间内到达乙地,则动车组列车匀速运动的速度v0应为()

A.

B.

C.

D.

答案:

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参考答案:A

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题型:阅读理解

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  You find a telephone number in the phone book, dial it, and then forget it. This is your short-term

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  Why do you forget something? Because you do not learn it in the beginning.This is the main reason

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but you do not learn them. Then you forget them.

1. How long does your short-term memory last?

A. As long as you want it to.

B. Less than thirty seconds.

C. Sixty seconds.

D. For a day or two.

2. Why do you forget?

A. We use our short-term memory instead of our long-term memory.

B. We don't learn what we hear or see.

C. We do not hear or see what we learn.

D. We are ill sometimes.

3. What's the phone book used for?

A. It's used for improving your memory.

B. It has a listing of friend's names.

C. You use it when you want to find a phone number you don't know.

D. You use it to buy a phone.

4. How can you best remember people's names?

A. List them down in a phone book.

B. Learn them.

C. Just ask them their names again.

D. Spell their names again and again.

5. If we want to have a good memory,we should______.

A. forget the useless things

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C. depend on our short-term memory

D. catch our long-term memory

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