16.You can't imagine that a well-behaved gentleman__________be so rude to a lady.
It’s already 10 o’clock. I wonder how it that she was two hours late on such a short trip.
_______ what would happen, none of them could find a way out.
Students who pass the test will be ______to the next grade, as has been announced.
The present financial crisis has put the world economy in a difficult .
Now, the world’s focus is all on Shanghai ______ the 2010 world Expo is to be held.