16、trial and error = to do something new by making experiments and occasionally falling 反复试验

The new computer system has been installed. But it's a bit trial and error at the moment - nobody really knows how to use it.

17、flesh and blood = your family 家人

I have to help him if I can - he's my flesh and blood.

18、down and out = someone who has no money at all who has to live on the street （贫困的，贫病交迫的）

There are too many young down and outs in London.

19、by and large = generally （大体上，总的说来，一般的说）

By and large, our customers prefer good service to low prices.

20、bring and buy = a fair where people try to raise money for a cause by bringing something that other people might want to buy （慈善救济性自由集市）

I'm making a cake for the school's bring and buy next week.

21、hide and seek = a children's game where one child hides and the others try to find him / her （捉迷藏）

Someone's been playing hide and seek with the TV remote control again.

22、to and fro = another way of saying " back and forth¹ " （往返地，来回地）

I'm exhausted² - I've been going to and fro all week!

23、over and out = something you say to show you have come to the end of your message （通话完毕）

The last thing they heard from the pilot was 'over and out'.

24、done and dusted = properly finished （完毕，了结）

Well, that's this project done and dusted. We need a holiday now.

25、wine and dine³ = to entertain someone lavishly⁴ （以好酒好菜款待客人）

He's well-known for winning and dining his business partners.

26、bread and butter = your main source of income, or the most important issue （维持生活所需的）

Health and education are the bread and butter issues facing the UK government.

27、spick and span⁵ = ( of a room, house, etc.) completely clean and tidy again （房间、屋子等打扫得干干净净的；整洁的）

Her house is spick and span at all times

28、wheel and deal = to make deals in a skillful and perhaps dishonest way when buying and selling things （讨价还价，玩弄手段，投机取巧）

If you need a new car, try speaking to John. He's a bit of a wheeler and dealer⁶.