关于need变否定句,问句的句型转换题目

问题描述:

关于need变否定句,问句的句型转换题目

need 表示“需要”或“必须”,作情态动词时,仅用于否定句或疑问句中.
在肯定句中一般用must,have to,ought to或should 代替.例如:
You needn't come so early.
Need I finish the work today?--Yes,you must.
注意:needn't have done“表示本来不必做某事而实际上做了某事”.例如:You needn't have waited for me.
“should have done”表示应该做到而实际上没有做到.
You should have started earlier.
“ought to have done”表示过去应做某事而实际未做.
You ought to have helped him (but you didn't)
切记:need作情态动词时仅用于否定句或疑问句中在肯定句中一般用must,have to,ought to或should代替
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