gerund or infinitive?

[hae mi]

Hi there!
My friend who is an English teacher, too, is confused right now.
That is because her student keeps on asking her questions about the English grammar rules, which she can't answer with proof. Some English books don't have specific grammar rules.
Can you help her?
She wanted to know when do we use the infinitive and when do we use the gerund. Is there a specific rule?

Thanks in advance!
Hae mi

[David L.]

Do you the infinitive, or the present participle?
Both present participle and gerund end in -ing, and these might be the confusion your friend is referring to.