how long；these days等 

附：常见的非延续动词转换为延续性动词表。

 1. 转换为相应的延续性动词。 

borrow — keep       

buy — have       

put on — wear        

catch/get a cold — have a cold 

get to know — know        

get to sleep — sleep

2. 转化为“be + 形容词/副词/介词/名词” 

close — be closed       

open — be open        

die — be dead       

become — be

fall sleep — be asleep             

wake up — be awake       

make friends — be friends    

fall/get ill — be ill         

lose — be lost/missing       

marry — be married  

leave (+地点) — be away (from +地点)   

come back/go back/return — be back        

begin / start — be on      

go out — be out 

finish — be over        

get up — be up       

go to bed — be in bed     

join — be in/be a member of  

get to/arrive in(at)/reach — be (in/at)         

come to/go to/move to — be (in/at)