1.What would you do if he cut in ine?（虚拟语气）
2.He spoke too fast for us to catch what he said.
He spoke so fast that we couldn't catch what he said.
3.= What would happen unless we could reach/get/arrive there on time?
或 = What if we couldn't reach/get there on time?（虚拟语气）
4.Eighteen-year-olds should be allowed to get their ears pierced (by parents).
5.If I won a lot of money,I would help the people who are poor.