Say what you would do if…(conditional) if i (to see) some schoolboys beating a smaller boy … if a child (to ask) me to help … if i (to hear) a person tell a joke about my best friend …

If I saw some schoolboys beating a smaller boy I would tell them to stop.
If a child asked me to help I would ask what's wrong.
If I heard a person tell a joke about my best friend I would defend my best friend.