1.to be in a rut：是指对每天同样的工作或是墨守成规一成不变的习惯，感到单调乏味
(to be tired of routine job; nothing new or excited) (rut 这个字本意是惯例或老套）。
例如： He has not been promoted for 20 years; he must be in a rut.（他廿年未获升级，一定感到单调枯燥。)
After thirty years of the same job, he feels he is in a rut.（干了卅年同样的工作，他觉得枯燥乏味。） 所以要放弃单调枯燥的生活方式，就是 to get out of the rut.
例如： If you hate your old job, you need to get out of the rut.（假如你不喜欢你的老工作，你就要走出乏味的日子。)

2. to be (或 become) fed up with (someone 或 something)： 意思是对某人或某事感到讨厌或厌倦（to get tired of; to be disgusted or to get sick of);
例如： I am fed up with his constant complaints.（他常常的抱怨令我厌烦。）
We all became fed up with his long speech.（他的长篇演说我们都觉得讨厌。）
The husband has been fed up with his wife's nagging.（老公对老婆的唠叨感到厌烦。）
如果只用「to be fed up」也可以：
I will not wait for her; I am fed up. (我不想再等她了；我厌了。)
(动词时态是：feed, fed, fed) 可见这句俚语似乎有「被动味道」，如果用 feed，意思又不同了