For short answers to past simple questions, don’t repeat the verb. Simply say: Yes, I did or No, I didn’t. We usually use the contraction in short answers.

Examples:
- Did you bite something hard? No, I didn’t.
- Did it hurt when it broke? Yes, it did.

Remember: The answer will be different with that wacky verb to be!
Examples:
- Were you eating something hard? Yes, I was.
- Was it very painful at the time? No, it wasn’t!

Use the prepositions in, at, or on to talk about time.

Examples:
In is used for periods of time.
in two weeks; in three months; in ten years

At is used for an exact time.
at 3 p.m.; at noon

On is used for days and dates.
on Tuesday; on August 6