The U.S. official said North Korea --- and Iran --- should follow in the steps of Libya, which last December said it would work__________ to allow international weapons inspectors to do their work. 

In his speech, Marks made the point ______ far more people died from smoking than from taking drugs.

—In early autumn Steve applied for admission to college. He wanted to go      but to Cornell University.—Oh, why not Harvard?

I thought she was famous, but none of my friends have ______heard of her.      

Of the two famous people, the former is Yao Ming, the      is Lin Shuhao.