needs repairing===needs to be repaired
need和require等词后面加动名词必须用主动表示被动,但加不定式时照旧,该用被动还用被动.比如：these trees require(need) looking after carefully＝ these trees require(need) to be looked after carefully.
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常用：need/require +doing sth（=to be done）（此句型主语大多为物）
例：My room is a mess.It needs _____.
A to be tidying up
B.tidying up
C.to tidy up
D.tidied up
（答案为B）
我的解答够详细了吧 不明白再问