Ответ:

1. She has already done her homework.

Has she done her homework yet?

She hasn't done her homework yet.

2. They have bought a new house.

Have they bought a new house?

They haven't bought a new house.

3. I have learnt this rule.

Have I learnt this rule?

I haven't learnt this rule.

4. We have travelled a lot recently.

Have we travelled a lot recently?

We haven't travelled a lot recently.

5. He has finished his novel.

Has he finished his novel?

He hasn't finished his novel.