He ________be at home because the light in his room is on.

According to the latest study，most traffic accidents     be prevented if drivers are careful enough．

That children ______meet with setbacks is a matter of necessity as they_____, so parents don’t worry about that.

 I didn’t know Headmaster Weng was away for Beijing. I       to his office yesterday.

—Look! That man looks like Mr．Brown．—It ________ be him, for I know he is at home．