Answer:
1. He _______ comb his hair by himself. His mother combs it for him.
a) could
b) can
c) couldn't
d) can't
2. My little brother ____ walk when he was six months old
a) can
b) can't
c) could
d) couldn't
3. Tom is really athletic. He _____ run very fast.
a) could
b) can
c) can't
d) couldn't
4. Could Jennifer eat her soup ____? No, she couldn't. It _____ too chili.
a) last night/ was
b) now/ were
c) yesterday/ wasn't
d) tomorrow/ isn't
5. _____ Adam ski? No, he _____
a) Can/ can
b) Could/ could
c) Could/ can
d) Can/ can't
6. David couldn't sleep well _____ because he was alone at home.
a) Now
b) last night
c) today
d) next week
I'm pretty positive these are all the correct answers to this. I hope this helps:)