U

under the weather身体不舒服

under no circumstances无论如何

up in the air悬而未决

ups and downs有喜有悲

W

With flying colors大获全胜

walking dictionary知识渊博的人

White lie善意的谎言

with open arms热烈欢迎

When in Rome do as the Romans do.入乡随俗

Y

You said it.你说对了

You bet.当然

You know that. 你听我说

You are telling me. 这还用说!

Yes-man唯唯喏喏的人