fight a losing battle

　　看字面意思应该可以大概了解这个短语的意思，就是打一场一点儿没有胜算的仗(to try to do something that you will probably never succeed in doing)。比如：

　　I’m fighting a losing battle against the mess in this house!

　　get back at somebody

　　这个表达的意思就是赤裸裸滴“报复”(to do something bad to somebody who has done something bad to you; to get revenge on somebody)。例如：

　　I’ll find a way of getting back at him!

　　for the life of me = however hard I try

　　就是“无论我多么的努力也…”。例如：

　　I cannot for the life of me figure out why they want to leave.