So mysteriously ______ missing that many puzzles wait to be solved.
Get involved in sports or other activities you enjoy______you can meet people who like what you like.
Why did you take a taxi____you could come here by bus?
Circus tigers, although they have been tamed, can _____ attack their trainer.
The patients believe that the doctor knows exactly how to put them _____.
They decided to leave the waiter a big _____ because the food and service had been excellent.