Present Simple:
Positive: She writes a letter to her grandmother every month.
Negative: He doesn't eat meat on Mondays.
Question: Do they study English on weekends?
Present Continuous:
Positive: They are watching a movie right now.
Negative: She is not working on her project at the moment.
Question: Is he playing football with his friends today?
Past Simple:
Positive: He wrote a poem last night.
Negative: She didn't go to the party yesterday.
Question: Did they visit the museum last weekend?
Past Continuous:
Positive: They were studying for the exam all night.
Negative: She wasn't cooking dinner when I arrived.
Question: Were they watching TV when you called them?