c1 when i look out of the door , i found that my car ..........(steal)
c2 when you ........ first .........( visit ) Hanoi?
c3 this is the firts time i  ..........(visit) Hanoi
c4 Right now , I ...........(need ) some help . What are you doing? Can you give me a land?
c5 last night , while i...........(write) a leter , the phone.......(ring)
c6 at this time yesterday, Mr. and Mrs . Browns's daughter..........(clean) the floor
c7 he hardly ..........(get) up before the sun (rise ) 
c8 in the last two weeks , we ...... (spent) our vacation in Halong Bay
c9 in two weeks , we (spend )our vacation in halong Bay
c10 Mary ..........(prepare) the meal before her friends came
c11 at the meeting , Join ........( speak ) until someone .......... (ask) him some questions
 c12 at the meeting, Join .........(speak ) until he .......(hear) other member's opinions
c13 why ............ you always................(argue) with each other? I'm not pleased with you at all
c14 i .........(try) to contact you all day. Where have you been?
c15 i ........(try) to contact you all day yesterday, bu i couldn't do that
c16 i .........(hard lock) the door when the phone rang 
17 my feet feel asleep because i ........(sit) on my heels
c18 my feet felt asleep because...........(sit) on myheels
c19 i had hoped tht he ........(forgive) me for not writing to him
c20 the robber.............(hang) for murder yesterday
c21 i..........(attend) Louisiana state University