1) came, had already left, had had, came
2) had spent
3) had missed
4) visited, hasn't been
5) stopped, looked, didn't see, sent, would meet, descovered, had recieved
6) had forgotten, had left, came
7) had stopped, was shining
8) had already begun, had had, was, had never been, liked
9) hadn't seen, had greatly changed
10) had spent, had learnt, had experienced, had come
11) burst, didn't remember, had tried
12) is working, has already gathered, is writing.