Ответ:

1. If I knew how to swim, I would go to the sea more often.

2. I suggest leaving before dawn.

3. As I had done my best, I decided that there was no point to worry over my exam results.

4. My mother had made me clean my room, before I could go to the cinema with my friends.

5. Katie refused helping me  with my homework.

Объяснение: