--- Hey, Mr. Smith, you are wanted on ______ phone. --- Who is calling? --- ______Mr. Green. I don’t know who he is.
_____ when one loses freedom does one know its value.
Little Jim is going to spend his holiday in Paris, _____ lives his uncle.
The problem is not _____ easy. Think _____ over.
It is so difficult a problem that _____ student in this class _____ work it out.
I think he is _____ to win, but I'm not sure.