内容正文:
英语 必修·第二册[WY]
Period Ⅱ Using language—Grammar & Vocabulary
Grammar(情态动词(1))
[观察句子,总结规律]
①... I was able to hold a knife and fork—and chopsticks!
②But there are still some dishes that Dad dare not try even after many years of marriage to my mother.
③Mum and I just have to find a way to get him into the kitchen!
④... we'd better not eat too much roast food as it may make us suffer from heat inside our bodies ...
⑤“You needn't try it if you don't want to,” Mum said ...
[我的发现]
以上五个句子都使用了情态动词:
(1)①句中的be able to意为“________”。
(2)②句中的dare意为“________”。
(3)③句中的have to意为“________”。
(4)④句中的'd better为________的缩写,意为“________”。
(5)⑤句中的need意为“________”。
答案:(1)能够,有能力 (2)敢,敢于 (3)不得不 (4)had better 最好 (5)需要
一、be able to
be able to意为“能够,有能力”,不仅有时态、人称和数的变化,而且还可以与某些系动词或情态动词连用(通常不与 can 连用),甚至还可以有非谓语形式。
He hasn't been able to get in touch with her.
他一直未能联系上她。
You might be able to persuade him.
你也许能够说服他。
I hope to be able to do the work.
我希望能胜任这项工作。
I regret not being able to help her.
我很遗憾未能帮到她。
易混辨析 can和be able to的区别
can和be able to都可以表示能力,前者泛指一般的能力,只有两种形式,即can, could;后者表示通过努力可以具备做成某件事的能力或实现某种状态,重点强调的是要有一个努力的过程。例如:
I can drive a car.(我会开车)
I will be able to drive the car in a week.(隐含着我努力一周后就能学会开车的意思)
二、dare
dare既可作情态动词,也可作实义动词。
1.dare作情态动词时,表示“敢,敢于”,后跟动词原形,常用于疑问句、否定句和条件句中。此时的dare没有人称、数和时态的变化,能单独构成否定和疑问。
Dare you climb that tree?
你敢爬那棵树吗?
He daren't go there because it is very dangerous.
他不敢去那里,因为那里很危险。
2.dare用作实义动词时,有时态和人称的变化,用do, does或did来构成否定句或疑问句。其后多接带to的不定式,有时to也可省去(尤其在否定句或疑问句中)。
She didn't dare (to) say a word, did she?
她一句话也没敢说,是吗?
I have never dared (to) ask her.
我从来不敢问她。
三、have to
have to表示客观上的必要,意为“不得不”,有时态、人称和数的变化,其否定形式为don't/doesn't/didn't have to,表示“不必”。其疑问句也借助do, does或did构成。
It's too late. She has to go home now.
天色太晚了,她现在得回家了。
You don't have to finish the work now.
你没有必要现在就完成这项工作。
易混辨析 have to和must的区别
have to表示一种客观的需要,而must表示一种主观的需要。此外,must还表示“偏要”“非得”的意思。
I have to attend an important meeting this afternoon.
今天下午我不得不参加一个重要的会议。
Why must you always interrupt me?
你为什么非得总是