bad hair day

　　诸事不顺的一天

　　A day on which everything seems to go wrong

　　I knew it was going to be a bad hair day when I couldn't find my keys in the morning.

　　当早上找不到钥匙的时候，我就知道这将是诸事不顺的一天。

　　get up on the wrong side of the bed

　　以不佳的心情开始一天

　　Begin the day feeling unhappy and uncomfortable

　　What's got into Ben today? Did he get up on the wrong side of the bed?

　　Ben今天咋了？为啥心情不好？

　　make someone's day

　　让某人感觉很开心

　　Winning the lottery really made my day.

　　中彩票真是让我太高兴了。

　　I've/We've Seen better days.

　　好日子过去咯。

　　If something or someone has seen better days, they are not in such a good condition as they used to be.

　　dog days

　　夏天很热的时候

　　Very hot days during summer

　　It's hard to get much work done during the dog days.

　　大热天没法做太多的工作。