need的具体用法我们老师和我们说don't need to do sth.,但我还是搞不清楚,求具体的need做情态动

“need”作为实义动词时,通常用法是
人＋need ＋to do 物＋need ＋doing 物＋need ＋to be done 例如： The room needs cleaning = The room needs to be cleaned. 房间需要打扫了. 另外,“need”作实义动词时后还可以直接跟名词.请看下面的例子： It is a question that needs very careful consideration．这是一个需要慎重考虑的问题 很简单的方法区别情态动词与实义动词：当need为情态动词时,意思是“必要”,否定为"needn't",后面大多接动名词,表示动作； 当need为实义动词时,意思是“需要”,否定为"don't need",后面大多跟名词.
作情态动词
1．need作情态动词无人称或数的变化, 后接动词原形,多用于否定句和疑问句中.如：You needn't worry.你不必担心.
2．由need引出的一般疑问句,肯定回答常用must或have to;否定答语常用needn't. 如：
—Need I answer the question? 我需要回答那个问题吗?
—Yes, you must. /Yes, you have to.是的,你必须回答./是的,你得回答./No, you needn't.不,不必了.
3．由must引出的一般疑问句,肯定回答用must,否定答语用needn't或don't have to.如：
—Must I do the work now? 我必须现在干这个活吗?
—Yes, you must /have to.是的,你必须做./No, you needn't /don't have to. 不,你现在不必做.