1. what (you/do) when i called you? i (watch) tv. 2. was mary busy when you came in? yes, she (study). 3. what time (the post / arrive) yesterday? it (come) while i (have) breakfast.

1) what were you doing when I called you?
I was watching tv
2) yes she was studing
3) what time did the post arrive yesterday?
It came while I having breakfast