18．A.fast B．well

　　C．alone D．often

　　解析：选B　根据文中的"At first they did not play ... They made mistakes."可知，一开始电脑下得并不"好(well)"，它们总出错。

　　19．A.weaker B．larger

　　C．slower D．stronger

　　解析：选D　根据下文中的"In 1997, a computer beat the best player in the world for the first time."可知，随着时间的推移，电脑更"擅长(stronger)"下国际象棋了。

　　20．A.old B．expensive

　　C．cute D．big

　　解析：选D　根据下文中的"It took up a whole room."可知，这个叫"深蓝"的电脑体积很"大(big)"。

　　Ⅱ.阅读理解

　　Bill Gates and the president of General Motors have met for lunch, and Bill is going on and on about computer technology."If automotive technology had kept pace with computer technology over the past few decades, you would now be driving a V­32 instead of a V­8, and it would have a top speed of 10,000 miles per hour，" says Gates."Or, you could have an economy car that weighs 30 pounds and gets a thousand miles to a gallon of gas. In either case, the sticker price of a new car would be less than $50. Why haven't you guys kept up？"

　　The president of GM smiles and says，"Because the federal government won't let us build cars that crash four times a day."

　　Why is that funny (or not funny, as the case may be)? Human beings love to laugh, and the average adult laughs 17 times a day. Humans love to laugh so much that there are actually industries built around laughter. Jokes, sitcoms and comedians are all designed to get us laughing, because laughing feels good. For us it seems so natural, but the funny thing is that humans are one of the only species that laughs. Laughter is actually a complex response that involves many of the same skills used in solving problems.

Laughter is a great thing - that's why we've all heard the saying，"Laughter is the best medicine." There is strong evidence that laughter can actually improve health and help fight disease. In this article, we'll look at laughter - what it is, what happens in our brains when we laugh, what makes us laugh and how it can make us healthier and happier. You'll