选择合适的句子补全对话。
| A.Can we have a dog, Mum? |
| B.He can't see. |
| C.Dogs are useful. |
| D.Grandma Zhang is deaf. |
Worker A: Grandpa Li is blind. _____ The dog helps him.
Worker B: _____ She can't hear. The dog helps her.
Mum: Wow! _____ They can do a lot.
Huanhuan: _____
Mum: No, we can't. I'm sorry.