It is ________ that he has been addicted to the drugs and has difficulty quitting it

Professor Smith, some students want to have a talk with you. ___ they wait here or outside?— Show them in now, please.

I ’m going to the post office.—________you’re there, can you get me some stamps

The Summer Palace is really beautiful. In fact, I doubt whether China has ________ park.

If I _____ one million dollars, I________ travelaround the world with my parents.