Odpowiedź:
Wyjaśnienie:
1) been
2) been
3) seen
4) sailed
5) been
6) spent
7) eaten
8) drunk
9) kissed
10) driven
11) had
12) known
13) read
14) been
15) heard
16) watched
17) been
18) studied
19) learnt
20) been
21) been
