When Carol _______ last night, I was watching my favorite show on television.
Correct Answer: EASY
Knowledge: Harmony of tenses
In the past, an event was happening when another event interrupted:
+ The happening is divided into the past continuous: S + was/were + V.ing => was watching
+ The event is interspersed in the simple past tense: S + V.ed => called
Last night, when Carol called, I was watching my favorite program on TV.