问题 单项选择题 案例分析题

某一除尘风机拟采用变频调速,技术数据为:在额定风量时交流感应电动机计算功率P=900kW,电机综合效率ηM100=0.92,变频器效率ηF100=0.976。50%额定风量工作时,电机效率ηM50=0.8,变频器效率ηF50=0.92。20%额定风量工作时ηM20=0.65,变频器效率ηF20=0.9。工艺工作制度:年工作时间6000小时,额定风量下工作时间占40%,50%额定风量下工作时间占30%,20%额定工作量下占30%;忽略电网损失。请回答下列问题,并列出解答过程:

说明除变频调速方式外,下列风量控制方式中哪种节能效果好?()

A.风机出口挡板控制

B.电机变极调速加风机出口挡板控制

C.风机入口挡板控制

D.电机变极调速加风机入口挡板控制

答案

参考答案:D

阅读理解

阅读理解。

     It's easy to make your own Internet page. The easiest way is to use a special program called a "web editor". You

can find these programs on the Internet.

     First think about some things to put on your Internet page by looking at other people's pages. You need to put

your Internet page on a bigger computer called a "host" which stores the pages so that other people can see them.

These computers are owned by special Internet companies. Our program may be able to help you find a host

computer which you can use for free, but some companies will charge money for this.

     To make your Internet page,    start up the program and write some text in the window,   then use the signs you

can see on the computer to put in pictures and make the text larger or smaller, and change the way your page looks.

You can also put photos on your Internet page.  First,   you need to put the photo in your computer, then use your

mouse to move the photo to the place where you want it. Choose the correct sign for putting photos onto the page,

then find the name of your photo in your computer. When you've found it,   choose that one with your mouse and

put your photo on your Internet page.

     You can also put signs on your Internet page to join it to other people's pages. Visitors to your page can follow

these signs to find out more about a subject. For example,   if    your page includes some information about Jackie

Chen, you could put on a sign that takes you to the page for his fan club.

     When you have completed your Internet page, you can put it on the Internet. After you put your page on the

Internet, anyone will be able to see it.

1. What is the first thing to do to make an Internet page according to the passage?

A. To buy it from a big company.

B. To get a program from the Internet.

C. To use another persons' page.

D. To make a program for it.

2. Why do people put signs for other Internet pages on their page?

A. To get money from the other people.

B. To get money from Internet companies.

C. To give more information about something.

D. To give people ideas about Internet pages.

3. According to the article, what things can you put on your Internet page?

A. Text, signs and photos.

B. Photos and films.

C. Text, signs and music.

D. Text and music.

4. What's the main idea of the article?

A. How to find programs on the Internet.

B. The way of making your own Internet page.

C. How to put photos on the Internet.

D. The way of putting your page on the Internet.

多项选择题