1:
a) was
b) was; while; were
c) were; while; were
d) were; when
e) were; when
2:
You were not studying when I called.
I was listening to the radio, so I didn't hear the alarm.
While we were sleeping in the tent last night, someone stole our axe.
While they were eating dinner he got back home.
At midday we were still driving.