问题 阅读理解

阅读下文,从各小题所给的四个选项中选出能回答所提问题或完成所给句子的最佳答案。

     Many children use the Internet to get useful knowledge and information, and to relax in their free time. 

 But some of them are not using"in a good way".  Here are some rules to make sure you are safe and have

 fun on the Internet.

     Make rules for Internet use with your parents. For example, when you can go online, for how long and

  what activities you can go online.

     Don't give your password (密码) to anyone else, and never lake out the following information, your

 real name, home address, age, school, phone number or other personal information.

    Check with your parents before giving out a credit (信用) card number.

     Never send a photo of yourself to someone in e-mail unless your parents say it's OK.

     Check with your parents before going into a chat room. Different chat rooms have different rules and

 attract different kinds of people. You and your parents must make sure it's a right place for you.

     Never agree to meet someone you met on the Internet without your parent's permission (允许).  Never

  meet anyone you met online alone.

     Always remember that people online may not be who they say they are. Treat everyone online as

 strangers.

     If something you see or read online makes you uncomfortable, leave the site. Tell a parent or teacher

  right away.

     Treat other people as you'd like to be treated. Never use bad language.

     Remember: not everything you read on the Internet is true.

1.  If you want a true friend on the Internet, you can _____ .

    A. tell the people what your name is 

    B. meet the people online alone

    C. write an e-mail about yourself

    D. get your parent's permission

2. It's good for children to _____ on the Internet.

    A. give password to others

    B. get useful knowledge and information

   C. give out a credit card number

   D. go into a chat room as they'd like to

3. The underlined phrase "leak out" in the third paragraph may mean " _____"

    A. give away                  

    B. leave out

    C. give out                    

    D. put away

4. If your parents don't agree, never _____.

    A. read anything on the Internet

    B. relax in your free time

    C. have a face-to-face meeting with anyone you meet online

    D. treat other people as you'd like to be treated.

5. This passage is mainly about " _____".

    A. How to use Computers

    B. Surfing on the Internet

    C. Information on the Internet

    D. Internet Safety Rules 

答案

1—5: DBACD

问答题

阅读短文,回答问题:

                                                                       新型发热材料    PTC

       PTC是一种新型的半导体陶瓷材料,它以钛酸钡为主,渗入多种物质后加工而成,目前家用的陶瓷暖风器、陶瓷电热水壶等就是用这种材料做成的。

       PTC有一个根据需要设定的温度,低于这个温度时,其电阻随温度的升高而减小,高于这个温度时,电阻值则随温度的升高而增大,我们把这个设定的温度叫“居里点温度”,用PTC材料制成的电热器具有发热、控温双重功能,应用十分广泛。

(1)家用固体电热灭蚊器就使用PTC陶瓷电热元件,图1为其电阻随温度变化的图像,由图可知,该PTC材料的居里点温度为               ℃。

(2)家用固体电热灭蚊器工作时的温度基本恒定在165℃左右,若它的温度高于165℃,电阻             ,功率              ,使其温度             (以上均填变化情况);反之,也能自动调节。因此用PTC材料制成的电热器具有自动调节功能。

(3)某同学利用PTC电阻设计了一个“过热自动报警电路”:将PTC电阻安装在需要探测温度的地方,当环境温度正常时,指示灯亮;当环境温度超过PTC电阻的居里点温度时,由于电阻变化,导致电磁铁磁性减弱,使警铃响。请帮他将图2所示的电路连接完整。

(4)你认为该“过热自动报警电路”的设计或在使用过程中有何不足?(指出一点即可)

                            图1                                                                                                        图2

判断题