问题 选择题

物体做匀加速直线运动,如果它的加速度为2 m/s2,那么它在任何1 s内的  (       )

A.末速度一定比初速度大2 m/s

B.后1 s的位移总比前l s的位移大2 m

C.后1 s的位移总是前1 s的位移的2倍

D.以上结论都不对

答案

AB

题目分析:加速度等于单位时间内速度的变化量,所以在任何1s内速度的变化量△v=at=2m/s.

AC、在任何1s内物体的末速度一定比初速度大2m/s;A正确C错误

B、由可得后1 s的位移总比前l s的位移大2 m;正确

D、AB正确所以D错误

故选AB

点评:物体的加速度等于单位时间内速度的变化量。

阅读理解

How to apply (申请) for a free mailbox (邮箱)? First you have to connect to the Internet and go to the homepage of the ICP providing free mailboxes. Then you will find an icon (图标), an agreement about the rules for using the free mailbox will appear. If you want to go, click the icon “I agree”. Then you have to fill in a form about your basic personal data, and the name and PIN (密码) of the mailbox. The PIN is the key to the mailbox. After finishing these, you will get a mailbox like this:your name @ mail server (for example:tvguide@mail.cctv.com.cn. “tvguide” is the name of the mailbox, and “mail.cctv.com.cn” is the name of the mail server.). The mailbox is separated (分隔) into two parts by a separator “@”, which is read as “at”. The former part is the name of the mailbox. The latter is the domain name (域名) of the mail server. All mails to you will be received by the server and put into your mailbox. You can read these mails on any computer on the Internet in the world, if you have the name and PIN of the mailbox.

1 If you want to send or receive an e-mail, you should first ____ .

A. apply for a mailbox                 B. buy a computer

C. go to the post office                D. fill in a form

2 When you get a FREE mailbox, you can send an e-mail ____ .

A. by paying some money            B. to anyone

C. without paying money            D. anywhere

3 The mailbox’s name in the e-mail address “editor@ew.com.cn.” is ____ .

A. ew                B. ew.com.cn     C. com.cn          D. editor

4 The writer mainly wants to tell us how to ____ in this passage.

A. send a letter by e-mail            B. read the e-mail on computers in the world

C. get a free mailbox                   D. find out one’s e-mail address

5 We can find the similar information in the book “____”.

A. Who Moved My Cheese           B. Surfing on the Internet

C. Bill Gates’ Story                      D. Harry Potter

单项选择题