1. be good at - be weak in
2. get into - get out of
3. turn on - turn off
4. turn down - turn up
5. at the front of - at the back of
6. on the left - on the right
7. at first - at last / in the end
8. take down - put up
9. catch up with - fall behind
10. fall asleep - wake up
11. get off - get on
12. in the day - at night
13. both... and... - neither... nor
14. more than - less than
15. take off - put on