official site as there are many knockoffs on the market today.

　　语篇解读：本文主要介绍了一款让老而慢的电脑焕然一新的设备。

　　21．The big computer companies are unhappy with Xtra­PC mainly because ________.

　　A．people will never buy any computer

　　B．it will probably affect their profits

　　C．it makes computers faster and more affordable

　　D．it's a new type of computer with creative design

　　解析：选B　推理判断题。根据第一部分的最后一句"The clever new device is saving people hundreds (even thousands) but the big computer companies aren't happy about it"可推知，这个新设备会使人们省钱，但会影响大型电脑公司的利润，故选B。

　　22．Which of the following is TRUE about Xtra­PC?

　　A．You should turn on your computer when plugging it in.

　　B．You should return it over a month to get your money back.

　　C．You can use it to change any old computer into a new one.

　　D．You can improve the performance of your old computer with it.

　　解析：选D　细节理解题。根据第一部分的第三句"Well, fortunately, there's a new device that has recently hit the market and it's absolutely giving old, slow computers lightning fast speed again"可知，有了这个新设备，老电脑的运行速度能大大加快，与第三部分的"Enjoy the New PC - In less than 15 minutes, you'll be shocked at the difference in the performance of your computer"呼应，故选D。

　　23．The underlined word "knockoffs" in the last paragraph probably means ________.

　　A．cheap copies of a well­known product

　　B．illegal websites that cheat people

　　C．false messages on the Internet

　　D．companies with a bad reputation

　　解析：选A　词义猜测题。根据画线词所在句可推知，要去官网买此设备，因为市场上有许多廉价仿冒品，故选A。

　　24．The main purpose of the passage is to ________.

　　A．tell readers how to speed up your computer

　　B．encourage readers to buy a new device

　　C．introduce a new invention to readers

　　D．explain to readers how Xtra­PC works

解析：选B　写作目的题。根据本文的整体内容可知，本文主要介绍了一款可以使老电脑焕然一新的设备，由此可推知，本文主要是向读者推介这款新产品，故选B。