Definition
To ensure someone understands the true facts of a situation; to clarify a misunderstanding.
使某人明白真相
I need to set her straight about this; she has some misconceptions about it.
我需要向她澄清這件事；她對此有一些誤解。
He has been misunderstanding me, so I need to set him straight.
他一直誤解我，所以我需要向他澄清。
At the meeting, I set the boss straight about his incorrect ideas.
在會議上，我向老闆澄清了他錯誤的想法。