knock up against . meet by chance巧遇；偶然碰到
I knocked up against my former teacher in the town this morning．今天早上在城里我遇见了我从前的那位老师。
I didn't expect to knock up against so many difficulties when I started on this subject．我没有料到这项目一开始就遇上了这么多的困难。
know about . know of . have information concerning知道…的情况
I didn't know about that．我不知道那件事。
know about . know of .be aware of the existence of知道…的存在；听说过
I know of an excellent little restaurant near here．我听说附近有一家优雅的小餐馆。
know apart . recognize the difference between 区分
The two brothers are so much alike that even their own mother hardly knows them apart．兄弟俩长得一模一样，连他们的母亲也很难区分得出来。
know backwards . learn very thoroughly完全了解
Every actor ought to know his lines backwards before he goes on stage．每一位演员在登台之前都必须背熟台词。
know from . tell the difference between辨别
He does not know right from wrong．他不辨是非。
know of . have heard of . have heard about听说过（没见过）
I don't know the Professor， but I know of him．我不认识这位教授，但是我听说过他。
known as . called by被称为
The actress likes to be known as May Diamond，although it is not her real name．这位女演员喜欢别人叫她“梅宝石”，虽然这不是她真正的名字。
He is known as a great statesman．众所周知他是一位伟大的政治家。
known for . famous for因…而出名
Hangzhou is known for the West Lake．杭州以西湖而著名。
known to . known by为…所知
He is known to everyone as an honest man．人们都知道他是一个诚实的人。
labour over . labour at . make a lot of effort about努力
Don't labour at your writing；try to make it easy and natural．写文章不要过分雕琢，要力图使其易懂自然。
labour for . work hard so as to gain努力工作以获取
Leaders of many nations are labouring for peace．许多国家的领导人致力于和平事业。
labour under . be burdened， troubled，or distressed by； suffer from the shortcoming of为…苦恼；困于
I think you must be labouring under a misunderstanding．我想你可能是受误解之苦。
She labours under speech handicaps because she stammers．由于有口吃的毛病，她说话很费力。
The firm has been labouring under difficulties for the past year．公司去年一直在困难中挣扎。
labour under . be misled or blinded by受…骗；受…蒙蔽
He's been labouring under the impression that we are prejudiced against him． However， we have been treating him with fairness．他一直以为我们对他有偏见，感到很苦恼，可我们一向对他是公正的。
lack in . fail to have any or enough缺少；不够
This car is lacking in speed．这辆车速度不够。
lag behind . fail to catch up with落后
The rest of the family had nearly reached the bank，but Jane was lagging behind．家里其他人都快要游到岸边，只有简落在后面。
later on . at a later time以后
I'll let you know later on．以后我会告诉你的。
laugh at . laugh to scorn；mock嘲笑
It is unkind to laugh at a person in trouble．对人幸灾乐祸有欠忠厚。
Don't laugh at her．不要嘲笑她。
laugh at .get amused about；make fun of 因…发笑
What are you laughing at,? 你们在笑什么?
That’s nothing to laugh at,．那没啥可笑的。
laugh at . show apathy or indifference to；reject一笑置之；付之一笑；轻视
He laughed at the idea．他对这个意见不以为然。
We advised him not to laugh at the official warnings．我忠告他不要对官方的警告不以为然。
The daring climbers laugh at danger．勇敢的登山者对危险付之一笑。
laugh away . continue laughing笑而不止
The crowd were still laughing away as they left the theatre．人们离开剧场时仍笑声不止。
I don't know why he was laughing away to himself all the time．我不知道为什么他自己一直在笑个不停。
laugh away . dismiss or get rid of with a laugh； scorn付之一笑；轻视
He just laughed away the enemy's threats．对敌人的威胁，他一笑置之。
Those who can laugh away all regrets are sure to live longer．能用笑声来解愁者必长寿。
There is no point in trying to laugh away this problem．It has to be dealt with realistically．对这个问题想一笑了之是不行的，必须切实加以处理。
laugh away . while away（time） with laughter以笑来消磨时光
He talks and laughs away his vacant hours．他谈笑风生，消磨无聊的空余时间。
We laughed away the time when we were together．我们说说笑笑消磨了我们在一起的时间。