It is really a matter of learning which verbs take 'to-infinitive' clauses and which take an '-ing' clause, Claudia. After some verbs, e.g. 'tell', 'advise', 'ask', 'to-infinitive' follows the object: ...

Adriana, learning English in Canada, writes: I have been studying English since I came to Canada, about four years now, but because there are so many exceptions to rules, it's hard for me to apply ...