on the line 岌岌可危;冒极大的险

【例句】
This is not the first time Mr Bernanke's reputation has been on the line.
伯南克的声誉并非第一次岌岌可危。

He wouldn't put his career on the line to help a friend.
他不会为了帮助朋友而让自己的事业受到威胁。