1) One minute question: "to infinitive" or "-ing"?
This is something students often ask about and it’s kind of a tricky point in English. However, here I’m going to illustrate the difference in meaning between the use of “to infinitive” and “-ing” with two verbs: stop and remember.
stop to do sth (sth = something)
Situation: They were hiking in the mountain. Around midday they stopped to eat in a meadow.
This means that they were walking and then they stopped walking because they wanted to start a different thing: they wanted to start to eat their sandwiches.
So, in this situation “They stopped to eat” means “They stopped walking and started to eat”).
“Stop to do sth” expresses two things: “stop and start”
Let’s compare this now to the “-ing” form: stop doing sth
Situation: You are reading a book and the phone rings. You stop reading and answer the phone.
This means that you were reading a book, and when you heard the phone ring, you stopped what you were doing (i.e. reading a book), because you wanted to answer the phone.
This is quite similar to the previous example, when you stop one activity to do another thing. The difference is in the focus.
“Stop doing sth” refers to the action that you interrupt, not the next action you want to do.
Compare this to “remember to do sth” and “remember doing sth“.
1) Please remember to switch off the light when you finish the meeting.
This means that you should remember that there is something you will need to do. (i.e. Please don’t forget that there is something important to do)
2) I remember seeing this film before.
This means that you remember something that you did in the past.
I hope these examples help you see the differences in meaning.