need在英語中用法有哪些
“need”既可以作情態動詞，也可以作實義動詞，扮演雙重角色，但是它們的用法不同，比較複雜，是升學考試中出題人鍾愛的一個考查點。
作爲情態動詞的“need”的用法與其他情態動詞“can”，“may”，“must”的用法基本相同：沒有非限定形式，即沒有不定式、-ing分詞或-ed分詞等形式;第三人稱單數現在時沒有詞形變化;下面是本站小編整理的一些關於need在英語中用法，歡迎大家閱讀！
need在英語中用法有哪些?
一、NEED與句子類型
(本條可參照ANY的用法。)
NEED可用於：
1.否定句/含有否定意義的句子
1)否定句
含not/hardly/never/nobody等詞語。
I needn’t say anything.
He need hardly advise me.
You never need tell me this or that.
Nobody need help me.
I don’t think he need come.(否定轉移)
注：NEEDN’T的意思其實有三種，即不必要/不一定/不應該，視具體語境而定。
2)含有否定意義的句子
含only/but/all/before/than等詞語。
He need only wait here.
You need but consider the matter to understand its importance.
That’s all that need be said.
Do not stay longer than you need.
There was another hour before I need go out into the cold.
2.疑問句/表示疑問的從句
1)疑問句(包括否定疑問句)
Need he say it again?
2)表示疑問的從句
I wonder whether/if I need see her.
3.條件句
含if/unless等詞。
If he need come, he will.
本條要點簡單概括起來就是，NEED不能用於肯定句。以下的各種用法也遵循這條規則。
二、NEED與時態
1.現在時
NEED常用於現在時。
You needn’t stay.
2.將來時
You needn’t have your blood pressure taken tomorrow.
3.過去時
NEED的過去式仍然是NEED。
1)過去時間由一過去時間狀語表示
He need not come yesterday.
2)過去時間由另一過去時動詞表示。
All he need do was to inquire.
It was clear that he need never trouble to get up at seven again.
I told him he needn’t be in a terrible fix.
注：表示過去的NEED常用於間接引語中。
(本條可參照must的用法)
三、NEED與虛擬語氣
1)NEED用於虛擬條件句
(本條可參照虛擬條件句的構成及用法。)
If money were useless, we need not struggle for it.
If you had been careful enough, you need not have suffered.
注：本條用法較爲少見。
2)NEED單獨使用：NEEDN’T HAVE DONE
(本條可參照SHOULDN’T HAVE DONE的用法。)
You need not have worried.
注：NEED HAVE DONE的形式較爲少見
Need you have scolded him so severely for his bad work? He had done his best.(否定意味)
He need have gone and sent that letter in person.(實際上沒有做)
四、NEED與推測
NEEDN’T表示“不一定”。
(本條可參照must/can的用法。)
1)NEEDN’T+BE
It needn’t be hot in Florida now.
對比：
It can’t be hot in Florida now.(一定不)
It must be hot in Florida now.(一定)
2)NEEDN’T+HAVE DONE
He need not have seen much of the world, though he is an old man.
對比：
He can’t have seen much of the world, for he is just a little boy.
He must have seen much of the world, for he has been traveling so widely.
五、NEED與問句
1)反意疑問句的構成
You needn’t go, need you?
2)答句的構成
--- Need he go?
--- Yes, he must/has to/needs to.
--- No, he needn’t.
(本條可參照must的用法)
六、情態動詞NEED與實義動詞NEED
1)使用範圍
作爲實義動詞的NEED有人稱、數和時態的變化，使用範圍更爲廣泛，不受句子類型和時態的限制。在肯定句、過去時和將來時的句子中，一般使用作爲實義動詞的NEED。
He needs to see a doctor straightaway.(此處needs to不能換做need，因爲本句是肯定句)
Will he need to start earlier?
注：
NEED TO BE DONE與NEED DOING可以互換，後者更爲常用(這裏的NEED均爲實義動詞)。
2)含義差別
NEEDN’T HAVE DONE與DIDN’T NEED TO DO表示“不必要”的時候，在意義上有所差別，前者表示“本不必做……”，實際上已經做了(NEED爲情態動詞);後者單純地表示“不必做……”(NEED爲實義動詞)。
