Transformer des phrases en utilisant Have toReformulation

Reformuler chacune des phrases suivantes en utilisant les modaux need ou must à la place de have to, de façon à conserver le sens initial de chaque phrase.

It doesn't have to be so difficult.

I have to finish my homework.

She has to be back at 7 p.m.

We have to look after our little brother.

I don't have to go to work today.

You have to tell us what you heard.

He has to keep the secret.