动名词作need,want,require,be worth的宾语时,用主动式代替被动式.
The washing-machine needs repairing.（或用：needs to be repaired）这台洗衣机需要修理.
The point wants referring to.这一点要提到.
This English novel is worth reading.这本英文小说值得一读.
The situation in Russian required studying.俄国形式需要研究.
请问这些例子为何不能用被动形式?