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一、表能力(ability)此时,can表示“会,能够”。否定句直接在can后面加not,疑问句则将can提到句首。如:
* 肯定句:She can drive a car.(她会开车。)
* 否定句:She cannot/can't drive a car.* 一般疑问句及其回答:Can she drive a car? Yes, she can./ No, she can't.* 划线部分提问:What can she drive?(假如划线部分为a car的话)
【注意】can与be able to1、be able to只能表示“会,能够”,但can还有其他意思,请参考接下去can的其他几种用法。
2、can只有现在时和过去时两种形式,而be able to则有多种时态形式。如:
* Will you be able to come tomorrow?(你明天能来吗?)
* This factory has been able to produce newly-devised sewing machines.(这家工厂已能生产新设计的缝纫机了。)
3、在be able to之前可加用另外一个助动词,且多用于否定或疑问结构,而can则无此用法。如:
* He may be able to come tomorrow morning.(他明早可能能来。)
4、用于否定结构,be able to表达一时情况,而can则表达往常情况。如:
* He is not able to swim today.(他今天不能游泳。)
* He can't swim at all.(他根本不会游泳。)
5、be able to后可接系表结构,表示一种状态或性质,而can没有这种用法。如:
* He was able to be cold about her now.(他现在对她可能有些冷淡。)
6、be able to有非谓语动词形式(即接在动词不定式或是以动名词或分词的形式出现),而can则没有。如: * I hope to be able to do the work.(我希望能做这项工作。)
* Being able to sing well, he decided to take part in the singing contest.(因为擅长唱歌,他决定参加歌唱比赛。)
* He left the claroom sadly, without being able to answer six of the questions of the test.(他难过地离开了教室,有六道题没答出。)