Ответ: Al. I… supper when my friend
phoned.
4) was having
A2. The telephone rang while I… TV.
1) was watching
A3. 1) humid

A4. 2) The girl was not
walking.

Bl. They had a very good time
while they were on holiday. (или while they were sunbathing on the beach)

Cl. Girl was making tea an hour
ago. (вообще-то правильно будет the girl made tea an hour ago.)