.Mary talked ________ she had seen the fire. But in fact she only heard of it from others.
Suddenly the idea came to me I might turn to Mr. Smith for help.
It is still unknown_______ caused the accident last Saturday.
____ wants to stay in a hotel has to pay their own.
The experiment shows that proper amounts of exercise ,if _______regularly, can improve our health.
It is one of the funniest things ____on the Internet so far this year.