作情态动词时，后接动词原形，

作实义动词时，主语是人，后接动词不定式（to

do

），主语是物时，接动词ing形式或to

be

done

，如

You

needn't

do

it

again.

It

is

cold,

you

need

to

wear

warm

clothes.

Your

shoes

need

mending.