My hair wants cutting.这里为什么要用cutting 而不用被动语态to be cut 或者bein

当主语是人时,want to do , 如 I want to go out.
当主要是物时,want doing ,如 The clothes want washing.
want 的动名词形式本身就有被动含义.
want doing 还可写成： want to be done
所以,My hair wants cutting. = My hair wants to be cut
类似的单词还有need
The car needs repairing = The car needs to be repaired.

首先want有两个语态：want to do
want doing
但是注意：hair是没有主动意识的。