語(yǔ)法專題六 情態(tài)動(dòng)詞
情態(tài)動(dòng)詞表示說(shuō)話人的語(yǔ)氣和情緒,本身詞義不全,不能單獨(dú)作謂語(yǔ),后面必須與動(dòng)詞原形一起構(gòu)成謂語(yǔ)。情態(tài)動(dòng)詞沒(méi)有人稱和數(shù)的變化,但有的情態(tài)動(dòng)詞有過(guò)去式。
考點(diǎn)一 can與could
1.表示能力,但could主要指過(guò)去的能力。表示“過(guò)去有能力成功做成某事”時(shí)通常用was/were able to。
The little boy can speak two foreign languages.
Could the girl read before she went to school?
Everyone was able to escape when the fire broke out.
2.表示可能(理論上或是邏輯判斷上,并不涉及此事真的發(fā)生),常譯為“往往會(huì),有時(shí)候可能會(huì)”,常用于肯定句中。
Accidents can happen on rainy days.
3.表示請(qǐng)求和允許。在問(wèn)句中could語(yǔ)氣比can要委婉。
You can go back home now.
4.表示驚異、懷疑、不相信等態(tài)度。主要用于否定句、疑問(wèn)句或感嘆句中。
How can you be so careless?
5.表示推測(cè),常用于否定句和疑問(wèn)句中,語(yǔ)氣較強(qiáng)。
He can't be in the classroom;the light is not on.
6.cannot/never...too/enough...表示“再……也不為過(guò)”。
You can never be too careful when driving a car.
7.cannot but do sth./cannot help but do sth./cannot choose but do sth.表示“不得不,只好做某事”。