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        情態(tài)動詞must的用法

        2010-05-29 07:17:12吳懷霞
        關(guān)鍵詞:否定句答語時用

        吳懷霞

        must的用法比較多,而且難掌握,現(xiàn)歸納如下;

        1. must的意義

        (1)表示責(zé)任,義務(wù), 意為“必須”。如:

        You must tell me the truth.

        (2)強(qiáng)調(diào)語氣的肯定,意為“一定要”。如:

        I must ask you about your family.

        (3)表示推測,意為“想必”。如:

        He must be at home; the light is on.

        2. must 的時態(tài)

        must只有一種形式, 在將來時里,可用must, 也可用 shall(will) have to。如:

        I must be at home tomorrow.

        I shall have to go there some day.

        must 一般不用于過去時態(tài),它的過去式常用had to代替。如:

        I had to go there yesterday.

        但在下列情況下must也可用過去時:

        (1)在間接引語中。如:

        He said that he must talk with his teacher.

        He decided that he must try to be on the side of the winner.

        I said you mustnt go there.

        (2)作推測解時。如:

        He must have gone to Beijing yesterday.

        (3)作“偏偏”解時。如:

        Just when they were about to go there, they must catch a bad cold.

        3. must的否定式及其答語

        (1)當(dāng)must意為“必須”時否定式是neednt。如:

        You must pay the money, but you neednt do so at once.

        Must I finish my homework now?

        Yes, you must./No, you neednt.

        其否定也可用dont have to。如:

        You must be back by 12 oclock. 變?yōu)榉穸ň鋺?yīng)是:

        You neednt be back by 12 oclock. 或 You dont have to be back by 12 oclock.

        (2)當(dāng)要表達(dá)“絕對不可,不許”時,其否定式是mustnt。如:

        You mustnt do that.

        You mustnt smoke, must you?

        I mustnt let anyone know.

        I must save money, mustnt I?

        (3)表示“推測”時 其否定式為cant。如:

        He must be there.

        He cant be there.

        (4)——May I come in?

        ——No, you mustnt.

        4. must 與 have to

        一般情況下可以通用。如:

        You must(have to) do as you are told.

        但:(1)表示主觀上認(rèn)為的責(zé)任或義務(wù)時用must。如:

        We must try our best to do it.

        (2)表示命令時用must。如:

        You must answer my question in English.

        (3)表示客觀條件不得不如此時,用 have to。如:

        He missed the bus and had to walk home.

        (4)must的否定式表示“絕對不可,不許, 禁止”,have to的否定式表示“不必”。如:

        You mustnt smoke in class.

        You dont have to go there.

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