Question

I was tired yesterday because I_____ well the night before.(not sleep)​

Answer 1

I was tired yesterday because I couldn't sleep well the night before.

We have used past tense in the second clause.

• If the first past consists of past indefinite tense, the second part must consist of past indefinite or past perfect.
• If the first part consists of present indefinite, the second part should be in present indefinite or future indefinite.
• The above sentence can also be written as: I was tired yesterday because I did not sleep well the night before.