need 既可以是情態動詞，也可以做實義動詞，做情態動詞後跟動詞原形
做實義動詞就用need to
當然need doing還有這個結構，是主動形式被動意義
The classroom needed cleaning.等同於
The classroom needed to be repaired.這時的need就是實義動詞了，因爲need做情態動詞的話，是不加ed的
I need finish the job quickly.
你需要一件毛衣用need後面接物品，你需要做什麼事情用needto後面接動詞
你想要一件毛衣用want後面接物品，你想要做什麼事情用wantto後面接動詞
need需要的意思是你缺少這樣東西，want想要的意思是你想得到但是並不是因爲你缺少。
你在特定情況下，比如有舞會，人家要求穿某種款式的衣服，如果你沒有，所以你需要買，用need，與你的主觀意願無關，是客觀條件造成你要去做的事情。如果你有，但是你覺得不好看，是你主觀願望想要買一件，那麼就是用want，與客觀無關。
wanttobuyanewT—shirt想要買一件新體恤衫buy爲動詞
wantanewT－shirt想要一件T—shirt表達了一種願望，後接名次
need 可做實義動詞，又可做情態動詞用。作爲情態動詞，只能用於疑問句，否定句和條件句。 need 作實義動詞時後面的不定式必須帶to ，need to是需要做某事的意思。 當need只用原形need後加do，否定形式爲need not。
拓展資料
need
1、需要必需
to require sth/sb because they are essential or very important， not just because you would like to have them
Do you need any help?
你需要幫忙嗎
It's here if you need it.
你要的話就拿去吧。
Don't go─I might need you.
別走——我可能要你幫忙。
They badly needed a change.
他們迫切需要一次變革。
Food aid is urgently needed.
迫切需要食物援助。
What do you need your own computer for? You can use ours.
你幹嗎還要自己買電腦你可以用我們的。
I don't need your comments， thank you.
謝謝，我不需要你來評頭論足。
[V to inf] I need to get some sleep.
我需要睡會兒覺。
He needs to win this game to stay in the match.
他得贏下這場比賽以免被淘汰出局。
You don't need to leave yet， do you?
你不必現在就走吧
[V -ing ， V to inf] This shirt needs washing.
這件襯衣該洗了。
This shirt needs to be washed.
這件襯衣該洗了。
note at reason
2、（表示應該或不得不做）有必要
used to show what you should or have to do
All you need to do is complete this form.
你要做的就是填好這個表格。
I didn't need to go to the bank after all─Mary lent me the money.
我最終還是不必去銀行了——瑪麗借我錢了。
need to
1、All right， no need to say any more.
好了，不要再說了。
2、I'll need to talk with you， but there's no hurry
我得和你談談，但不着急。
3、I think we need to go away and think about this.
我認爲我們有必要走開一下去考慮這件事。
4、You should write-protect all disks that you do not usually need to write to.
你應該對你通常不需要寫入內容的磁盤進行寫保護。
5、Adults need to live their own lives and that's difficult with children.
大人需要過他們自己的生活，但有了孩子就很難做到了。
