need的用法老师讲过,需要做...用needtodosth,而need可以看作是情态动词也可以看作是动词,所以needn't后面必须是dosth.可是我看电视时发现有一句和老师讲的不一样,Neednottoknow(无需知道).那need

Question

need的用法 老师讲过,需要做...用need to do sth,而need可以看作是情态动词也可以看作是动词,所以needn't后面必须是do sth.可是我看电视时发现有一句和老师讲的不一样,Need not to know(无需知道).那need究竟有怎样的用法呢?可以帮我分析一下needn't do sth和needn't to do sth这两者的区别吗?

Answer 1

1. 你老师讲得没错.
情态动词: need (not) do sth
行为动词: need sth/sb
need to do sth
need sb to do sth
sth need doing=sth need to be done
名词: there be no need for/of sth
there be no need (for sb) to do sth
in need (of...)
2. 否定形式应该是 needn't do sth
而need not to do sth也是有的(但不能缩写成needn't to do sth)
因为to do sth这个不定式本身也有否定式,不定式的否定全部是在to前加上not/never等否定词
3. 但是两者在翻译差别很大啊,要记住.
needn't do sth 没有必要做某事
need not to do sth 不做某事有必要
如: You needn't ask him.
You need not to smoke as a student.