Chia động từ trong các câu sau

chia động từ
1 Columbus...........(discover) America more then 400 years ago
2 he fell down when he..........(run) towards the church
3 we..........(still live) there when our father died
4 they..........(play) pingpong when their father comes back home
5 By Christmas, i ........(work) for you 6 months
6 i .......(be) to New York three times this year
7 i will come and see you before i ........(leave) for America
8 the little girl asked what .........(happen) to her friend
9 John .......(read) a book when i saw him
10 he said he.....(will) return later
11 Jack....(open) the door
12 my sister .......(look) for you since yesterday
13 Jack ......(just paint) the door
14 the train .....(leave) half an hour
15 we ......(not see) Doris since last Sunday
16 when i last saw him, he ......(live) in London
17 after i ......(have) lunch, i looked for my bag
18 by the end of next year, George ..........(learn)english for 2 years
19 the man got out the car ,.......(walk) round to the back and opened the boot
20 for several years his ambition..........(be) to be a pilot
21 henry........(go) into the restaurant when the writer was having dinner
22 he will take the dog out for a walk as soon as he........(finish) dinner
23 before you asked , the letter .......(write)
24 ask her to come and see me when she ........(finish) her work
25 oil......(float)if you pour it on water
26 the dancing club .........(lie) north of the city
27 Almost everyone.........(leave) for home by the time we arrived
28 by the age of 25, he.........(write) two famous novels
29 while her husband was in the army, Janet......(write) to him twice a week
30 i couldn't cut the grass because the machine..........(break)down a few record for the long jump
31 i have never played badminton before . This is the first time i ......(try ) to play
32 since he ......( leave) , i have heard nothing from him