Odpowiedź :
1 had left
2 had walked
3 hadn't put
4 had closed
5 had lost
1. By the time we got to the station, our train (leave) had left.
2. After I (walk) had walked the dog, I did my homework.
3. Someone stole my bike because I (not put) hadn't put the bike lock on it.
4. The shop (close) had closed by the time we got there.
5. When she got home, she realized that she (lose) had lost her key.