obligation

If it's a request from none other than you, I can hardly turn it down.

I owe him considerably.

She had no choice but to turn down his proposal.

She has to take care of that elderly man.

She had no choice but to marry the old man.

She said she had to go right away.

You must not be discourteous to your benefactor.

I would never break the law.

She needs to help him out.

She has to make a living on her pension.

She strove to fulfill her duty.

She doesn't need to go herself.

She had to go herself.

She knows perfectly well what she should do now.

She has to go shopping in the afternoon.

She'll probably have to cook for everyone.

She had to practice piano for two hours.

She had to give a speech in front of a large audience.

She has a lot of work she has to do.

She fulfilled her duty.

She has to pay the price of the book.

She has to go there.

She absolutely has to come here.