Here are the corrected sentences:
- Corrected: Where were you yesterday?
- Corrected: Yesterday, it was sunny.
- Corrected: I was very happy because the test was easy.
- Corrected: We were at the beach last weekend.
- Corrected: The film starts at 4 o'clock OR The film started at 4 o'clock.
- Corrected: My parents were at a party on Saturday night.