乙烯制冷压缩机出口出现超压现象，应果断打开火炬阀，一旦超压消除，应立即关闭放火炬阀，

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                                                            Vision-phones (可视电话)

      Radio, telephone and television are widely used in the world, When you switch on the radio, you can listen.

But when you use telephone,not only can you listen to others but also you can chat with them,however, you

can't see anything at all. Television is much better than both of them. People can watch TV and listen to it, but

they can't take part in what they see. 

     Today, some people are using a type of telephone called vision-phone. With it two people who are talking can

see each other.

     Vision-phones can be of great use when you have something to show the person whom you are calling, It

may also have other uses in the future. Some day you may be able to call up a library and ask to read a book

right over your vision-phone, You may be able to do some shopping through it, too. Perhaps In the near future,

vision-phone will come into wide use in our everyday life.

1. According to the passage, we can guess that the _______ was invented last. [ ]

A. radio

B. television

C. telephone

D. vision-phone

2. Maybe the vision-phone can take the place of _______ some day. [ ]

A. the radio

B. the telephone

C. the television

D. all the above

3. Through a vision-phone we can _______. [ ]

A. take medicine

B. order what we need

C. travel around the world

D. try on clothes

4. In the future, you can use a vision-phone to _______. [ ]

A. read a book

B. ask an assistant to read a book for you

C. ask an assistant to bring you a book

D. ask an assistant to do some shopping for you

5. Which of the following is NOT true? [ ]

A. Vision-phone is more advanced than radio-telephone or television.

B. People will use vision-phone in the future more than now.

C. Vision-phone will be helpful in people's life.

D. It is impossible to do shopping through vision-phone.

小明有10块大白兔奶糖，从今天起，每天至少吃1块，那么他一共有______种不同的吃法．

心理健康教育

为确诊以下哪项检查最快速、简便、准确

A．在病灶取标本镜下检查

B．病理组织学检查

C．分泌物细菌培养

D．PCR

E．血清抗体检测

网络割接管理主要是针对网络设备、（）等割接工作的指挥、调度和管理。

A、线路

B、退服

C、扩容

D、搬迁