Как ответить на на вопрос how often do you play football?

Смотря как часто играешь в футбол. если не часто, то - i do not (often)  play  football. но точнее наверное сказать к примеру  - i  play football once (twice и т. п.) a month (или можно употребить week? year? two weeks и т. п.) 

Как часто ты играешь в футбол?  

1.in

2.at

3.at

4. at

5       in

6     in

7       in

8         at

9.   in  

listen, ivan singing in the room.

he doesn't see that i look at it, as he reads something with a great interest.

call him now. i think that he doesn't sleep yet.

look at the person who sits at a window. he/she is our lawyer.