[词性] 二十三、情态动词 2 [ have to ] [ ought to ] [ dare ] [ be able to ] [ needn‘t ] [ had better ]

[ have to ]

have to 得意思接近 must，但是 must 强调说话人的意愿

        [例1]：We must remember this. 我们必须记住这个

        [例2]：You must take care of her.        你必须照顾她

have to 表达客观上的必要性，表达不得不，否定形式表示 不必

        [例1]：I have to go to work on time.        我不得不按时上班

        [例2]：We have to be careful in such matters.        处理这类事情，我们必须小心

        [例3]：He has to do a lot of reading.        他得看很多书

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① 一般现在时态

主语非三单 + have to + 动词原型 + 宾语

        [例1]：We have to help him.        我们不得不帮他

        [例2]：You have to sleep.        你必须得睡觉

主语非三单 + have to + be + 表语

        [例1]：My students have to be careful.        我的学生必须要小心

主语非三单否定句        don't have to

主语三单 + has to + 动词原型 + 宾语

        [例1]：She has to take pills.        她必须要吃药

        [例2]：The doctor has to help him.        这个医生不得不帮他

主语三单 + has to + be + 表语

        [例1]：The girl has to be careful.        这女孩必须得小心

主语三单否定句        doesn't have to

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② 一般过去时态

主语 + had to + 动词原型 + 宾语

        [例1]：They had to jump into the river last night.        昨晚他们不得不跳河里

        [例1]：They didn't have to jump into the river last night.        昨晚他们不必跳河里

        [例2]：I missed the last bus and had to walk home.        我错过了公车，不得不走路回家

主语 + had to + be + 表语

        [例1]：You had to be careful yesterday.        昨天你不得不小心

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③ 一般将来时态

主语 + will + have to + 动词原型 + 宾语

        [例1]：We will have to take the bus tomorrow.        我们明天必须得坐公交

        [例1]：We will not have to take the bus tomorrow.        我们明天不必坐公交车

        [例2]：We will have to help him as much as we can.        我们将不得不尽量帮他

主语 + will + have to + be + 表语

        [例1]：You will have to be careful in the future.        以后你必须得小心

注意：一般将来时态，也可以用 be going to + have to 构成

        [例1]：I am going to have to take the bus tomorrow.        我明天不得不坐公交车

        [例2]：She is going to have to go home tomorrow.        她明天必须得回家

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主语：have to 一般没有 现在进行时态 和 现在完成时态

[ have to ] 疑问句 否定句

        [例1]：Do you have to leave soon?        你一定要马上离开吗？

        [例2]：Does she have to go with you?       她一定要跟你去吗?

        [例3]：You don't have to say sorry.        你不必说对不起

        [例4]：She doesn't have to take the bus.        她不必坐公交车

注意：过去时态 did.. have to / didn't... have to

           将来时态 will... have to / will not... have to

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主语：have got to 和 have to 意思和用法一样

        have got to 在口语缩写成 've gotta

        [例1]：I've gotta go now = I have to go now.        我现在得走了

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[ ought to ] 

注意：一般 ought to 没有疑问句，只有肯定句和否定句，也没有时态变化

否定句在 ought 后面加 not，ought not to

        [例1]：We ought to get up early.        我们应该早起

        [例2]：We ought to be careful.        我们应该小心

        [例3]：We ought not to eat too much sugar.        我们不应该吃太多糖

        [例4]：I ought to go home today.        我今天应该回家

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[ should ] 应该

should 可以做助动词，也可以做情态动词，做情态动词得时候，就是 应该 的意思

否定句 should not        疑问句 should 放开头

        [例1]：We should get up early = We ought to get up early.        我们应该早起

        [例2]：We should help the poor people.        我们应该帮助这些穷人

        [例3]：We shouldn't sit in the office all day long.        我们不应该一整天坐在办公室里面

        [例4]：Should we stay here?        我们应该留在这里吗？

        [例5]：Should we help the old man?        我们应该帮助这个老人

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[ dare ] 敢

dare 可以做实义动词，也可以做情态动词，在肯定句里面做实义动词，

在否定句，疑问句，条件句里面做情态动词

注意：dare 在肯定句中做实义动词，后面不能跟动词原型，要跟动词不定式短语 做宾语

        [例1]：I dare to hit him.        我敢打他

        [例2]：I dare not hit him.       我不敢打他

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否定句中的 dare 是情态动词，dare not 情态动词，后面跟动词原型 hit，构成复合谓语

注意：dare 做情态动词时没有人称变化，但有过去式 dared

        [例1]：I dare not look at her. = I don't dare look at her.        我不敢看她

        [例2]：She dare not look at me. = She doesn't dare look at me.        她不敢看我

        [例3]：I dared not drink beer last night. = I didn't dare drink beer last night.

                昨晚我不敢喝啤酒

注意：dare 在带有 否定意思的句子中 也可以做情态动词

no one  nobody 不定代词 没有人

主语 + 谓语 + 宾语，一般现在时态，不定代词做主语

        [例1]：No one supports me.

        [例2]：Nobody loves me.

        [例3]：Nobody dare love me.        否定句，dare 情态动词

        [例4]：No one dared speak of it.        没有人敢谈及此事

        [例5]：He never dared stay long.        他从来不敢待久

        [例6]：I hardly dared look at her eyes.        我几乎不敢看她的眼睛

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疑问句，条件句中的 dare 也是情态动词，跟动词原型，变一般疑问句要将 dare 移动到主语前面，也可以用助动词 do

        [例1]：Dare she look at me?        她敢看我吗？

        [例1]：Does she dare look at me?

        [例2]：Dared you drink beer last night?        你昨晚敢喝啤酒吗？

        [例2]：Did you dare drink beer last night?

注意：dare 在肯定句中，是及物动词，后面要跟 动词不定式短语 做宾语

        [例1]：I dare to go home alone.

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[ be able to ] 能，可以

be able to 做情态动词，跟 can 的差不多用法，但 be able to 存在时态用法

        [例1]：I am not able to answer your question.        我不能回答你的问题

        [例1]：I can't answer your question.

        [例2]：Are you able to type? = Can you type?        你会打字吗？

be able to 存在时态变化

① 一般现在时态

        is able to        am able to        are able to

        [例1]：I am able to repair computers.        我会修电脑

        [例2]：Are you able to repair computers?        你会修电脑吗

        [例3]：She is able to swim.        她会游泳

        [例4]：Is she able to swim?        她会游泳吗？

        [例5]：She is not able to swim.        她不会游泳

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② 一般过去时态

        was able to        were able to

        [例1]：She was able to drink ten bottles of beer last night.        她昨晚能喝十瓶啤酒

        [例2]：She wasn't able to find you last night.        她昨晚无法找到你

        [例3]：You were able to eat 3 bowls of rice ten years ago.        十年前你能吃三碗饭

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③ 一般将来时态

        will able to

        [例1]：I will be able to earn much money.        我以后可以赚很多钱

        [例2]：I will not be able to come to your wedding.        我不能参加你的婚礼了

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④ 现在完成时态

        has been able to        have been able to

        [例1]：He hasn't been able to leave the house since his accident.       

                他出事故以来，一直不能出门

        [例2]：We have been able to earn one million yuan a year.        我们已经可以年赚百万了

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[ needn't ] 

need 本来是实义动词，可以做情态动词，只有否定格式 needn't 才能做情态动词，

含有否定意义的句子或者少数的条件句，疑问句里面也可以做情态动词

主语 + needn't + 实义动词 + (宾语)

没有人称要求，没有时态要求

        [例1]：I needn't go home.

        [例2]：I needn't teach English in the future.

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① 用于否定句，表示 不必，没必要，needn't 做情态动词没有人称变化

        needn't + 动词原型        needn't + be + 表语

        [例1]：I needn't prepare my lessons.        我不需要备课

        [例2]：She needn't come here early.        她不需要早来这里

        [例3]：We needn't be worried.        我们不必担心

        [例4]：They needn't send me a receipt.        他们不必寄收条给我

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② 用在带有否定意义的句子中

        need 在含有否定意义的句子里面也做情态动词，跟动词原型构成复合谓语

        [例1]：I need hardly tell you the truth.        我用不着告诉你真相

        [例2]：Nobody need be afraid of catching the disease.        谁都不必害怕染上这种病

        [例3]：I don't think you need worry.        我认为你不必担心

注意：如果一定要用 need 表达 我必须买一个房子这样的意思

        [例1]：I need to buy a house.        need 实义动词，to buy a house动词不定式短语作宾语

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[ had better ] 最好

had better 情态动词，后面跟动词原型，表示 最好 ，缩写 'd better

had better 没有疑问句，没有时态结构变化，不受主语人称影响

had better 有否定格式 had better not，表示 最好不 的意思

主语 + had better + 实义动词 + (宾语)

主语 + had better + not + 实义动词 + (宾语)

        [例1]：You'd better take a nap after lunch.        你最好午饭后睡个午觉

        [例2]：You'd better not talk like that.        你最好不要那样说话

        [例3]：We'd better stop arguing.        我们最好停止争吵

        [例4]：You had better not meet net friends alone.        你最好不要一个人去见网友

主语 + had better + be + (表语)

主语 + had better + not + be + (表语)

        [例1]：You'd better be careful.        你最好小心

        [例2]：You'd better not be late.        你最好不要迟到

had better 后面也可以跟 助动词原型 be + 现在分词，表示 最好立即做某事

        [例1]：I think I'd better be going.        我想我最好还是走了

        [例2]：We'd better be getting our clothes ready.        我们最好穿好衣服