1. Hurry up or you will be late.

→→ If you don't hurry up, you will be late.

2. She is very busy, so she can't help me now.

→→ If she wasn't/weren't busy, she could help me now.
3. I can't apply for that job because I don't know English.

→→ If I knew English, I could apply for that job.

3. You're unfit because you don't take exercise regularly.

→→ If you took exercise regularly, you would be unfit.

4. Keep silent or you'll wake the baby up
 
->If you don't Keep silent,  you'll wake the baby up

5. Stop talking or you won't understand the lesson

->If you don't  Stop talking,  you won't understand the lesson