1.The report criticized boardroom fat cats who award themselves huge pay increases.
报告批评董事大亨们为自己大幅提薪。
fat cat:
(slang) A rich person who contributes to a political campaign.
(slang) Any affluent person who is perceived to have profited from the labour of others.
2.I'm afraid physics will always be a closed book to me.
恐怕我对物理永远是一窍不通了。
closed book:
(idiomatic) A person or thing that cannot be easily understood; someone or something incomprehensible or puzzling.
3.He reads me like an open book.
他对我了如指掌。
open book:
(idiomatic) A person who through naivete responds candidly to questions or openly displays their emotions or intentions.
4.She was the only one without a date, so she felt like a fifth wheel.
她是唯一没有约会对象的人，因此她感到自己很多余。
Do you want to go to the park with us? I'd love to go out with you, but I hate to be a third wheel.
你想跟我们一起去公园吗?我想和你们一块去，可我不想当电灯泡。
third wheel:
(idiomatic) A person or thing that serves no useful purpose.
(idiomatic) An unwanted third party accompanying two people on a date.
fift wheel:
(idiomatic) Anything superfluous or unnecessary.
5.He's such an eager beaver when it comes to teamwork.
每次团队工作，他都干劲十足。
We all like working with eager beavers.
我们都喜欢和有干劲儿的人共事。
eager beaver:
(idiomatic, colloquial) One (especially a child) who is very excited or enthusiastic to begin a task.