The politician saw red when the journalist questioned his integrity.

saw 是动词 see 的过去式，意思是"看到、察觉"。 red 本义是"红色"，在英语中常用来象征"愤怒"，因为人在愤怒时面部会充血变红。 saw red 是一个固定短语，字面意思是"看到红色"，实际表示"突然大怒"的意思。