问题 多选题

物体从静止开始作匀加速直线运动,第10s末的速度为2m/s,则下列说法中正确的是(  )

A.前10s内的位移为10m

B.任意1s内的速度的增量都是0.2m/s

C.第10s内的位移为2m

D.第6s内的位移比第5s内的位移多0.4m

答案

已知物体初速度等于零,第10s末的速度为2m/s

由v=v0+at

得:a=0.2m/s2  故B正确

物体前10s内的位移,由x=

1
2
at2

得x=10m  故A正确

C、第10秒内的位移等于前10秒内的位移减去前9秒内的位移,大小为8.1m,故C错误.

D、与C选项解法相同,第6s内的位移比第5s内的位移多0.2m,故D错误.

故选:AB

阅读理解

阅读理解。

     Canadians like to say "Thank you" when others help them or say something kind to them. People of

many other countries do so, too. It's a very good habit.

     You should say "Thank you" when someone passes you the salt on the table, or opens the door for you,

or says you have done your work well.

    "Thank you" is used not only between friends but also between parents and children, brothers and sisters,

husbands and wives.

     "Excuse me" is another useful short expression. When you hear someone say so behind you, you know

somebody wants to walk past without touching you.

     It's not polite to interrupt (打断) others when they are talking. If you want to speak to one of them, say

"Excuse me" first, and then begin talking. You should also do so when you want to make any noise before

others.

1. ________ like to say "Thank you".

A. Canadians

B. Few people outside China

C. People all over the world

2. You should say "Thank you" when ________.

A. you have done something wrong

B. someone opens the door for you

C. you pass the salt to others on the table

3. If you want to walk past somebody without touching him, you'd better say "________" first.

A. Excuse me

B. I'm sorry

C. Don't move

4. When you hear others say you write very well, you should say "________".

A. Excuse me

B. No, it's not good

C. Thank you

5. Which of the following is true?

A. People say "Thank you" among the members of a family and friends.

B. We don't say "Excuse me" by day.

C. People say "Excuse me" only between brothers and sisters.

单项选择题