I have good reason to be suspicious.
我的懷疑有充分理由。
There is no reason to disbelieve him.
沒理由不相信他。
Are you angry with me for some reason?
你是因為某個原因生我的氣了嗎？
This was the real reason for her call.
這是她打電話的真實原因。
He said no but he didn't give a reason.
他說不行，但沒有說明原因。
There seems no reason to doubt her story.
似乎沒有理由懷疑她所說的話。