本文向大家介绍的英语口语表达是：blowing hot and cold。从字面上看，“hot and cold”是一会儿热，一会儿冷，所以这个短语其实是形容人“跟天气一样地反复无常，拿不定主意”。
这个习语出自伊索寓言。有个人冬天跟森林之神一起吃饭，先是在手上哈气取暖，后来又吹气让热汤凉下来，森林之神认为他反复无常，一会儿嫌冷一会儿嫌热，马上下逐客令，说：“I will have to part with a man who can blow hot and cold from the same mouth.”
- He keeps blowing hot and cold about immigrating to Canada.
他对移居加拿大一事始终拿不定主意。 - His enthusiasm for the job blows hot and cold.
他对这工作的热情反复无常，时冷时热。 - He's a man given to blowing hot and cold; you just can't tell what he's standing for.
他这个人翻云覆雨，弄不清他究竟主张什么。
