As is so often pointed out,knowledge is a two-edged sword which can be used____for good or evil
The girl behaved in a strange way. You could not________her mind.
Mr. Black must be worried about something. You can________it from the look on his face.
When the lawyer asks you questions about the case, you should be________.
—How many days are there in February? —________thirty days.
Tom is________a common worker. How disappointed his parents are to see he hasn't gained great achievements!