Chỉ ra đại từ quan hệ thừa trong câu.
The number of options (1) that are available to us with (2) which to fill our leisure time is increasing all the time. While previous generations, (3) who lived before the electronic age, had musical instruments and card games (4) that they played to pass the time, we have PlayStations, computers, televisions and stereos. Although parents (5) whose teenagers spend a lot of time on these activities might worry about the effect (6) which it is having on them, for most of us they provide harmless fun, (7) which is becoming more important as life becomes more stressful. The television programmes (8) which we watch and the computer games (9) that we play all entertain us and, although there will always be people to (10) whom they seem a complete waste of time, the effect (11) that they have on society cannot be ignored. Entertainment is something (12) which we all need and, as long as we’re willing to pay, there will always be someone (13) who is willing to provide it.