新概念英语第四册第十七单元语法和句型(教学用)

新概念英语第四册第十七单元语法和句型Lesson 17 A man-made disease 人为的疾病In the early days of the settlement of Australia, enterprising settlers unwisely introduced the European rabbit. This rabbit had no natural enemies in the Antipodes, so that it multiplied with that promiscuous abandon characteristic of rabbits. It overran a whole continent. It caused devastation by burrowing and by devouring the herbage which might have maintained millions of sheep and cattle. Scientists discovered that this particular variety of rabbit (and apparently no other animal) was susceptible to a fatal virus disease, myxomatosis. By infecting animals and letting them loose in the burrows, local epidemics of this disease could be created. Later it was found that there was a type of mosquito which acted as the carrier of this disease and passed it on to the rabbits. So while the rest of the world was trying to get rid of mosquitoes, Australia was encouraging this one. It effectively spread the disease all over the continent and drastically reduced the rabbit population. It laterbecame apparent that rabbits were developing a degree of resistance to this disease, so that the rabbit population was unlikely to be completely exterminated. There were hopes, however, that the problem of the rabbit would become manageable. Ironically, Europe, which had bequeathed the rabbit as a pest to Australia acquired this man-made disease as a pestilence. A French physician decided to get rid of the wild rabbits on his own estate and introduced myxomatosis. It did not, however, remain within the confines of his estate. It spread through France where wild rabbits are not generally regarded as a pest but as a sport and a useful food supply, and it spread to Britain where wild rabbits are regarded as a pest but where domesticated rabbits, equally susceptible to the disease, are the basis of a profitable fur industry. The question became one of whether Man could control the disease he had invented.【语法点】情态动词+完成体不定式【课文原句】It caused devastation by burrowingand by devouring the herbage which might have maintained millions of sheep and cattle. 【闯关例句】1. have done sthmust have done sthcan have done sthcould have done sthmay have done sthmight have done sth2. present status positionmust be a teacher3. be doing sthmust be watching TVpossibilityought to have done sthshould have done sthYou must have left your handbag in the theatre.你一定是把手提包忘在剧院了。

Jack ________（肯定有事耽误了）, or he’d be here by now.The prisoner ________（一定是从这条路逃走的）must have escaped this way, for there arefootprints.They are sweating all over. They ________（一定在踢足球）.No matter how busy you were, you ________（至少可以寄张明信片）.You were stupid to go skiing there---you ________（会把你的腿摔断）.I could have climbed that mountain ten years ago.十年前我本来是能够登上那座山的。

I ________（本可以成功）, but I didn’t try my best,so I feel regretful.You could have helped him in those circumstances.在那样的情况下，你本来可以帮助他的。

If Peter had been driving faster, he ________（可能丧命了）.If it weren’t for having to leave England, I might have been tempted by that oil company’soffer. 要不是因为得离开英国的话，我可能会接受是由公司的聘请了。

It would be a good thing to write to him, I should have thought. 给他写封信倒是很好，但是我没有想到。

Martha did not accept the bad news. She ________（本应把这当成一个寻求其他机会的信号）.If you doubt his ability, you________（本不该雇他）in the first place.I think I should have thought sometimes that youcouldn’t help thinking of the past. 我想我本来应该想到你不仅会想起过去。

The policeman said that the motorist ought to have stopped, but that he must have lost his head.警察说驾驶员当时是得停下来，要不然命都丢了。

In my opinion the offender ought to have beenimprisoned, but they let him off with acaution. 我认为罪犯应该判刑，但是他们给他个警告就释放了。

This road ought to have been finished six months ago. 这条路六个月前就该修好。

You oughtn’t to have driven that car with the brakes out of order. You might have had aserious accident. 你原不该驾驶那辆制动失效的汽车。

你当时有可能会遇到严重的意外事故。

She ought not to have taken his books without asking him. 没有问他她本来不应该把书拿走。

【语法点】主语从句【课文原句】It later became apparent that rabbits were developing a degree of resistance to this disease, so that the rabbit population was unlikely to be completely exterminated.【闯关例句】（1）It is certain that he will win the match.（2）It is true that he has made a veryimportant discovery in chemistry.（3）It is very likely that they will hold a meeting.（4）It is strange that he should do that.（5）It is important that we all should attend the meeting.（6）It is strange that the man should have stuck to his silly ideas.（7）It i s a pity that we won't be able to go to the south to spend our summer vacation.（8）It is still a mystery what caused the accident.（9）It is said that he has gone to shanghai.(=He is said to have gone to shanghai) （10）It is known to all that the gun powder was first invented by the Chinese.（11）It is su ggested that the work should be done with great care.（12）It seems that he has seen the film.(=He seems to have seen the film)（13）It happened that the two cheats were there. (=The two cheats happened to be there)________that he didn’t come. 很遗憾他没来。