瞬间动词转换成持续性动词
瞬间动词用于完成时态不能与一段时间状语连用，须转换成持续性动词。

1.用相应的延续性动词替换的有：
buy---have borrow---keep put on----wear
catch/get a cold---have a cold
come/go/become---be 等。

eg. 1.We have had the TV set for 3years.
2.I have kept the book for 2 weeks.
2.转换成be+名词的有：
join the army----be a soldier
join the Party----be a Party member
go to school----be a student 等。

eg. 1.He has been a soldier for 5 years.
2She has been a student for 2 months.
3.转换成be+adj/adv.
die—be dead finish—be over begin---be on
leave---be away move----be out of
put on---be on open---be open close---be closed fall asleep------be asleep 等。

eg. He has been dead for 5 years.
4. 转换成be+介词短语
go to school----be in school
join the army---be in the army 等。

eg. 1.She has been in the army for 2 years.
2.He has been in school for 9 years.
5.通过去掉短语中的结束性动词
get to know---know
begin to study---study
come to work----work
eg. 1.We have known each other for 10 years.
2.He has study Chinese for 2 years.
*瞬间动词完成时的否定式已成为一种可延性状态，因此可以和表示一段的时间状语连用。

eg. 1.I haven’t heard from her for 6 months.
2.I haven’t bought anything for 2 months.
leave --- be away, borrow --- keep, buy --- have, begin/start --- be on, die --- be dead, finish --- be over, join --- be in+组织机构, be a member of+组织机构, open sth --- keep sth open, fall ill --- be ill, get up---be up, come here --- be here, go there --- be there, become --- be, come back --- be back, fall asleep --- be asleep, get to/ arrive/reach --- be (in), leave --- be away from, get to know --- know, go (get) out →be ou t，put on→ wear；catch a cold →have a cold,get married---be married等。