Be at one’s wits’ end:
To be so worried, confused, or annoyed that you do not know what to do next.
意思是 “因找不到解决问题的办法而感到一筹莫展、束手无策，不知道下一步该怎么办”。wit意为智力，机智，wits为复数，加单引号为复数名词的所有格。字面意思就是到了一个人的智力的尽头了。
例句
My baby won’t stop crying. I’m at my wits’ end about what to do next.
我的宝宝一直哭个不停。我完全不知道该怎么办。
I’m at my wits’ end trying to understand this work schedule – I don’t know what I should be doing now.
我绞尽脑汁想弄明白这个工作日程安排表，但还是没看懂。我真不知道现在该做什么。
He’s at his wits’ end trying to find enough money to pay his rent. He could be evicted any day.
他绞尽脑汁想凑钱付房租，却一筹莫展。他随时都有可能被赶出去。
