Ответ:
1)knew
2)learning
3)began
4)visiting
5)selling
6)working
7)didn't receive
8)asking
9)working
10)went
11) writing , didn't send
12)make
13)didn't see
14)answered
15)arriving, arrived
16)switched
17)went
18)didn't finish
19)told
20)answered
21)sending
22)doing, typing
23)going
24)discussing
25)came, landing
26)leaving
Не совсем правильно везде, но если что сами разбиретесь)))))))