③ for和since引导的短语都表示“一段时间”,所以谓语动词应该用延续性动词,不能用非延续性动词。延续性动词表示该动词可以延续一段时间,如:live, work, study, teach, stay等,非延续性动词是指该动词所表示的动作不能持续,是短暂的、瞬间完成的,如:borrow, come, arrive, get, leave, die等。
许多非延续性动词可以用意思相同或相近的延续性动词来表示:
leave ---- be away from arrive ---- be in
go ---- be away come ---- be in / at finish ---- be over
buy ---- have borrow ---- keep die ---- be dead
join ---- be in/be a member of begin ---- be on
如:
He has gone He has been away for an hour
I have bought a watch I have had the watch for several days