问题 填空题

管理人员从一池塘中捞出30条鱼做上标记,然后放回池塘,将带标记的鱼完全混合于鱼群中.10天后,再捕上50条,发现其中带标记的鱼有2条.根据以上收据可以估计该池塘有______条鱼.

答案

设该池塘中有x条鱼,由题设条件建立方程:

30
x
=
2
50

解得x=750.

故答案为:750.

阅读理解

Life on-line can be a much richer experience when you aren’t restricted to just written words and still pictures.Even if you’re new to the Net,you’ve probably heard about multimedia on-line—listening to audio,watching animations and videos,even playing in three-dimensional space.Sound and movement make information come alive.

To experience it,you’ll need special pieces of software called plug-ins.The term “plug-in” refers to a small,add-on piece of software which extends the capabilities of your web browser,like Netscape Navigator or Microsoft Explorer,turning your computer into a radio or TV.

When you arrive at a web page which contains a file requiring a plug-in which you don’t have,you will usually receive a message asking if you want to get it by downloading it and installing it into your computer.Most of the time,the installation will be automatic.

Occasionally,you’ll run into a downloaded file which needs to be decompressed or un-zipped before installation.Once installed,plug-ins run automatically,without you having to do anything.

Many multimedia controls still need to be obtained from the developer but are installed automatically.

Shockwave is a good example of this.All you need to do is go to the Macromedia site and click on the link to install the ActiveX control.The rest happens automatically.The next time you go to a “Shocked” website,the Shockwave control loads and plays the movie.

Most plug-ins and controls can be downloaded for free on the Internet,although not all will work with every system.Some of them,for instance,only work with Windows 95.

小题1:Plug-ins can help us to do all of the following except _________.

A.listening to music

B.watching animations and videos

C.playing three-dimensioned games

D.searching for information on the net小题2:The correct explanation about “plug-in” is _________.

A.a radio or TV connected with a computer

B.a small,add-on piece of hardware which improves your web browser

C.a small,add-on piece of software which can turn your computer into a radio or TV

D.a small,add-on piece of software like Netscape Navigator or Microsoft Explorer小题3:When we go to a “shocked” website a second time,_________.

A.we should go to the Macromedia site and click on the link to install the Active X control

B.the shockwave control loads itself and plays the movie for us

C.we will be asked whether to download the shockwave control or not

D.we have to buy the shockwave control and load it小题4:Most of the time,how can we get a plug-in before automatic installation?

A.We have to buy it from the developer.

B.We have to borrow it from the developer.

C.We have to rent it from the developer.

D.We can obtain from the developer without paying.

单项选择题