Ответ:

1.

B: was talking

2.

Dan: were you talking

Steve: was telling

3.

A: Were you watching

B: was reading

4.

A: Were you playing tennis

B: wasn't playing, was doing

Объяснение:

past continuous строится по такой структуре:

+: подлежащее+was(I, he, she, it)/were(you,we,they)+Ving (глагол с окончанием ing)

-: подлежащее+was not/were not (wasn't/weren't)+Ving

?: Was/Were+подлежащее+Ving

указывает на длительное действие в прошлом, происходившее в конкретное время. сигнальными словами могут быть: yesterday at 6 o'clock, yesterday morning и т.д