to blow hot and cold 出爾反爾(成語)
英文釋義
(IDIOM) To vacillate; to change one's opinion in a weak, indecisive way.
例句
The boss often blows hot and cold, depending on his mood, and so no one can predict his decisions on anything.
這位老闆總是出爾反爾,一切取決於他的情緒,所以沒人能預測他的任何決定。