1A rains
2C were/ would not
3B had known / would have invited
4D Had I known
5D If I am not
6A Had the plane not
7B had worked
8B had finished
9D had taken
10B began
11C not going
12C capable of doing st : có năng lực làm gì
13C telling ( regret V-ing : tiếc vì đã làm gì , regret to V : tiếc vì phải làm gì )