____ the police know the killer's identity, they are getting close to catching him.
He dropped the ______ and broke it.
Please never do such things _______ other people.
The old professor travelled from one school to another, _______ first-hand information about the education situation in China.
The old man is so ______ that he has to ______ his meals every day.
—Your mother becomes more and more forgetful. —Yes. She searched for her cellphone for a whole day last Sunday but it ___ in her coat pocket the next day.