B2.1 - 6B Grammar: can could, be able to

2 can / 3 couldn't / 4 can't / 5 couldn't / weren't able to / 6 Can / Could / 7 be able to / 8 be able to / 9 being able to / 10 can't / 11 be able to / 12 'd be able to / could / 13 couldn't / 14 was able to / 15 been able to