Answers to grammar exercises "used to"

New Pass Trinity book, p.22, Grammar focus
Ex.4a 
1. didn't you use to like 2. used to love 3. did you use to play 4. did your parents use to work 5. used to come with 6. used to be
Ex.4b
1. both possible 2.both possible 3. used to 4.used to 5. didn't use to
Ex. 4c
1. used to   2.didm't use to   3. used to   4. used to   5. used to   6. used to   7.didn't use to

First memory: The bicycle
Ex. 3
Dahl walked alone, the kid's hands were off the handlebar and across his chest., we went back pedalling and he was 20 yards away.
Second memory: The great mouse plot
1. Its owner was a horror
2. Picture number 2