a/
1. I'll
2. I'll
3. I'm going to
4. We're going to
5. I'll
6. I'm going to
7. I'll
8. I'm not going
b/
1. Is Helen going to buy the food?
=> No, she isn't. Sue is.
2. Are you going to make a cake?
=> No, I'm not. Kate is.
3. Are they going to light the candles?
=> No, they aren't. We are.
4. Is Jack going to dress up in traditional clothes?
==> No, he isn't. Pete is.
5. Are we going to set off the fireworks?
=> No, we aren't. Dad is.