13.1

1. +
2. has gone
3. forgot
4. went
5. had
6. has broken

13.2

1. +
2. +
3. have forgotten
4. arrested
5. has improved
6. have finished
7. applied
8. was
9. has been
10. broke, did ... happen, fell

13.3

1. +
2. +
3. did Shakespeare write
4. OK
5. OK
6. The Chinese invented
7. were you born
8. OK
9. Albert Einstein was … who developed