1. I didn't do exercise. Since I had a lot of homework, I didn't have time to do exercise.

Question

2. I didn't exercise. Since I had a lot of homework, I didn't have time to exercise.

3. I didn't take exercise. Since I had a lot of homework, I didn't have time to take exercise.

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Which expressions are grammatical? Are all grammatical? Then, which ones are commonly used?

Answer 1

All are grammatical, but 2 is the very best phrasing.