1. If I found a bag in the street, I will take it to the police.

2. If I found a bag in the street, I would take it to the police.

3. If I found a bag in the street, I took it to the police.

4. If I found a bad in the street, I‘ll be taking it to the police.

5. If I found a bag in the street, I have taken it to the police.