3)
1) We were having breakfast when the telephone rang.
2) She met a lot of friendly people while she was working in Russia
3) When they left the gallery, the sun was shining.
4) The students were laughing when the professor came in.
5) While the children were sleeping, their parents watched TV.
6) It started to snow while she was coming back from the opera
7) When Pete opened the door, it was raining
8) While Evgeny was sunbathing his wife was swiming in the sea
9) heard; was talking
10) was taking ; ate
11) was texting ; arrived
12) broke; was skateboarding
13) listened ; was cooking
14) was driving ; stopped
15) noticed ; was watching
16) fell off ; was painting
17) were waiting ; surfed
18) became ; was travelling
19) What were you doing when you heard about this accident?
20) My sister said that she didn't feel happy so I talked to her