The two things are the same in outward form but different _____.
Nothing that you say can change his mind, ________?
The smoggy weather has made us realize ________ terrible problems we are faced with.
—How unhappy your roommate looks! —Yes, but he's not willing to tell me what it is ________ is troubling him.
When the millionaire was young, he was very poor. Only by doing parttime jobs during the summer holiday ________ afford to pay his college fees.
So quickly ________ is a possibility today may be a reality tomorrow.