How_________I help them to understand when they won’t listen to me?

It has been announced that candidates _______ remain in their seats until all the papers have been collected.

— Is John coming by train ? — He should, but he ______ not. He likes driving his car. 

We would have called a taxi yesterday if Harold ______us a ride home.

It’s high time that he settled down in the city and ____ a new life.