Modal verbs

They ... do it now, can't they?

You ... have been there, must you?

There ... anything wrong with him, can there?

They ... have been at home, can they?

He ... swim very well, when he was young.

He said you ... stay here.

I knew he ... to do this job.

He ... imagine what they were doing.

John ...believe that Helen was in London.

He said that I ... visit him any day I liked.

Helen asked whether she ... see them today.

We knew that he ... take part in the excursion.

He said they ... come soon.

I thought it ... be a chance of a lifetime.

His mother said the boy ... doing his lessons.

She said they ... already arrived.