2016年職稱英語(yǔ)衛(wèi)生類備考語(yǔ)法：情態(tài)動(dòng)詞

關(guān)于情態(tài)動(dòng)詞：

①常見的情態(tài)動(dòng)詞有：can (could) ,may (might), must ,shall (should), will (would), dare (dared) , need等,另外,have to、had better也當(dāng)作情態(tài)動(dòng)詞使用。情態(tài)動(dòng)詞后面必須加動(dòng)詞的原形。

②can表示體力、腦力方面的能力或客觀的可能性�？谡Z(yǔ)中, 在詢問(wèn)或說(shuō)明一件事可不可以做時(shí),常用“can”代替“may”。情態(tài)動(dòng)詞“can”的過(guò)去式是“could”,否定式是“cannot”通常縮寫成“can't”,“could”的否定式是“could not”,通�？s寫成“couldn't”。如：Can I help you?(要幫忙嗎?)/ He can swim.(他會(huì)游泳)/ That can't be Mr Li.(那不可能是李先生)

③ may表示允許、請(qǐng)求或可能性,用may提問(wèn)時(shí),肯定回答一般用Certainly或Yes,you may.;否定回答一般用can't或mustn't. 如：May I ask you a question?—Certainly.(可以問(wèn)你一個(gè)問(wèn)題嗎?當(dāng)然可以)/ You may go now.(現(xiàn)在你可以走了)/ It may be in your pocket.(它可能在你的衣袋里)

④ must表示“必須”、“一定”的意思。表示“必須”時(shí)否定形式是mustn't;表示“一定”時(shí),否定形式是“can't” 如：We must be very careful when we cross the road.(我們過(guò)馬路時(shí)一定要非常小心)/ It must be Jack.(那準(zhǔn)是杰克)/ I haven't seen Kate today. She can't be here.(我今天沒(méi)有看到過(guò)凱特,她不可能在這里)

[注意]用must(必須)進(jìn)行提問(wèn)時(shí),肯定回答用must,否定回答用needn't;用must(一定)進(jìn)行提問(wèn)時(shí),肯定回答仍用must,但是否定回答用can't.如：Must we clean the room before we leave? –Yes, you must.或No, you needn't.(我們走之前必須要打掃房間嗎?是的,必須打掃。/ 不,不需要。) / Must she be in the room? –Yes, she must.或No, she can't.(她一定在房間里嗎?是的,一定。/ 不,不可能在。)

⑤ “have to”表示“不得不”、“必須”。We'll have to leave now for it is very late at night.

have to的疑問(wèn)形式是：助動(dòng)詞+…+have to,否定形式是：助動(dòng)詞+not+have to或者用needn't.如：Do you have to stay until 8 o'clock?(你得呆到8點(diǎn)鐘嗎?)/ You don't have to do so.(=You needn't do so.)(你不用這么做)

⑥ shall在問(wèn)句中,可表示征求對(duì)方意見,與第一人稱連用;在陳述句的第二、三人稱的主語(yǔ)后或表示“命令”、“警告”、“允許”等。如：Shall we go to the zoo this weekend?(我們這個(gè)周末去動(dòng)物園好嗎?)/ He shall bring his own book next time.(他下次必須帶自己的書來(lái))

⑦ should可表示“勸告”、“建議”、“驚奇”等意思。We should speak to old people politely.(我們應(yīng)該禮貌地對(duì)老人講話)

⑧ will表示“意愿”、“決心”等意思,一般與第二人稱連用。如：Will you please close the door for me?(請(qǐng)你替我把門關(guān)上好嗎?)/ I will teach you a lesson.(我要教訓(xùn)你一頓)

⑨would表示過(guò)去的“意愿”、“決心”等。He would sit near the fire every time he returned home.(每次他回到家中總要坐在火爐邊)

would也可以表示現(xiàn)在的情況,表達(dá)說(shuō)話人向?qū)Ψ教岢龅囊��?語(yǔ)氣比“will”婉轉(zhuǎn)、客氣。在日常會(huì)話中,“我想要…”通常用“I would like to”或“I should(I'd) like to”來(lái)表示。如：Would you like to have a rest at the moment?(你現(xiàn)在想要休息一下嗎?)

would還可以表示過(guò)去經(jīng)常發(fā)生的事情。如：Every year parents would tell their children about the boy who would save his people.(每一年父母?jìng)兛偸窍蚝⒆觽冎v述這個(gè)將會(huì)拯救他的人民的男孩的事)

⑩ need表示“需要”,用于疑問(wèn)句或否定句。“need”作實(shí)義動(dòng)詞時(shí),在肯定、否定、疑問(wèn)句中都可以用。如：He needn't do it in such a hurry.(他不需要如此匆忙地做這件事)/ He needs some help.(他需要一些幫助)/ He doesn't need to bring his football socks then.(那么他就無(wú)須帶上足球襪了)

⑾ dare是“敢”的意思,用法幾乎與“need”完全相同,即在疑問(wèn)句和否定句中,可以作情態(tài)動(dòng)詞,后面用不帶“to”的動(dòng)詞不定式。在肯定句中和實(shí)義動(dòng)詞一樣,后面的動(dòng)詞不定式要帶“to”。How dare you say I am a fool?(你竟敢說(shuō)我是個(gè)傻瓜?)/ He didn't dare to touch the red button.(他不敢觸碰那個(gè)紅色的按鈕)

⑿ ‘d better (do)(“最好是”)一般也當(dāng)作情態(tài)動(dòng)詞使用,否定式是：'d better not (do). 如：You'd better sit here and say nothing.(你最好坐在這兒不講話)/ You'd better not speak because he is sleeping.(你最好不要講話因?yàn)樗�正在睡覺(jué))