A. Are you interested in working for us?
A1. I’m not very good at learning languages.
A2. Sue must be fed up with studying.
A3. What are the advantages of having a car?
A4. Thanks very much for inviting me to your party.
A5. How about meeting for lunch tomorrow?
A6. Why don’t you go out instead of sitting at home all the time?
A7. Carol went to work in spite of feeling ill.
A8. can also say ‘instead of somebody doing something’, ‘fed up with people doing something’.
B. Before ‘-ing’ after ‘-ing’ (e.g. Before going out, I phoned Sarah. (not Before to go out) What did you do after leaving school?), can also say ‘before I went out ~’ and ‘~ after you left school.’
B1. by ‘-ing’ (to say how something happens), without ‘-ing’.
C. to ‘-ing’, to is often part of the infinitive. (to do/ to see etc.) But to is also a preposition (like in/ for/ about / from etc.)
C1. If a preposition is followed by a verb, the verb ends in ‘-ing’: in doing, about meeting, without stopping, etc. So, when to is a preposition and it is followed by a verb, we must say ‘-ing’.