As is often pointed out, knowledge is a two-edged weapon which can be used ________ for good or evil.
Recent pressure at work may___ his behavior.
If he starts talking about his past, you will never___ from him.
To our joy, the operation is___ success and the patient is now out of ___ danger.
Please ____ your sister to bring the ticket for the concert.
Your story is perfect; I’ve never heard___ before.