1、K1、keep doing, keep on doing这两个词组均用来表示“不断做”的意思，但在涵义上有所不同。keep doing和keep on doing都可表示“不断（老是）做某事”的意思，强调动作连续不断，每隔一会儿发生，这时两者可以换用。不同的是keep doing中的doing是动名词，作宾语。例如：John always kept (on) asking questions.约翰总是问个不停。News of successes keeps (on) pouring in.捷报频传。keep doing还可表示连续不断的动作或持续的状态。keep on doing则没有这种用法
2、。例如：We kept working in the fields in spite of the rain. 尽管下雨，我们还是坚持在地里干活。Why do the dogs keep barking?这些狗为什么不停地叫？2、keep sb. from doing sth., keep sth. from sb.keep sb. from doing sth.相当于prevent (or: stop) sb. from doing sth., 意为阻止某人做某事。keep sth. from sb.则表示“将某事瞒着某人”的意思。例如：What kept you from joining
3、me? 什么事情使你不能和我在一起？We must keep them from getting to know our plans.我们必须防止他们知道我们的计划。It seems that she keeps something from us.她好像有什么事瞒着我们似的。Why did you keep the truth from me? 你为什么向我隐瞒真相？3、kind, sort, type这一组词都表示“种类”，常可互换使用。kind系普通用语，其含义较模糊，它所指的种类可用任何标准区分，但着重以事物的自然属性和内在性质为标准来区分。kind常和type换用，但在表示动植物的种
4、类,族及牌类游戏时，不能用type代替。如：There are different kinds of animals in Shanghai Wild Animal Park. 在上海野生动物园有许多不同的动物。Computers can actually do many kinds of work. 事实上，电脑能做许多不同的工作。sort也为普通用语，比kind更口语化，其概念同kind一样很不严密，两者常可互换，但sort常掺杂说话人的主观色彩，带有轻蔑与贬低的含义。如：We talked of all sorts of subjects.我们谈了各种话题。These sorts of
5、people are ready to eat anywhere.这种人总是走到哪里吃到哪里。4、know, recognizeknow为“认识，熟悉，知道”，表示认识或熟悉某人，某事，某地。它可作及物或不及物动词，后接名词，代词及从句作宾语，另可接含形容词及不定式的复合结构。如：Who knows, perhaps he doesnt care about me at all.谁知道呢，也许他根本不在乎我。Have you known Oliver long? I knew him as long ago as the year 1984. 你很久以前就认识奥利福了吗？我在一九八四年的时候就
6、认识他了。I didnt know you were coming today.我不知道你会来。Ive never known you so cheerful.我从来不知道你这么开朗。I know her to be a fool.我知道她是个傻瓜。recognize为“认出，认清，承认”，表示能认出原来认识或曾经见过的人，物及地方，以及承认某事物的客观存在。它只作及物动词，后接名词，代词及从句作宾语。如：You have grown so tall that I scarcely recognize you.你长成这么高，我几乎认不出你来了。Did you recognize your un
7、cle at once? 你是不是一下子就认出你的叔叔来了？Presently I recognized that we were in the Atlantic Avenue. 现在我知道我们在亚特兰大大街。5、keep up, keep up withkeep up既可是动副型短语动词，也可是动介型短语动词，主要表示“（斗志，价格等）不低落”，“维持，继续”等意。可以用于被动语态。例如：Their spirit kept up well in spite of hardships.虽有困难，但他们并不气馁。Prices still keep up.物价仍旧上涨。I hope the wea
8、ther will keep up.我希望天气继续晴朗。They entered into a correspondence which was kept up for almost 10 years. 他们开始通信了，并且把这种通信联系保持了十年之久。keep up with是一个动副介型短语动词，后须接名词做其宾语，表示“跟上，与.同步前进”的意思，即有强调并行不悖，不掉队的意味。只用于主动语态。例如：He walked so fast that I could hardly kept up with him.他走得那么快，我简直跟不上了。We must keep up with the
9、times. 我们应该跟上时代。6、knock down, knock out这两个短语动词是动副型，knock既可作及物动词用，也可作不及物动词用。两个短语动词均在句中作谓语，只是意义不同。1. knock down主要表示下列几种意义：1.击倒，打倒 2.拍卖给 3.拆卸，拆散 4.（强迫）减价。例如：He was knocked down by a lorry.他被一辆卡车撞倒了。He knocked his opponent down.他将他的对手击倒。These old houses are to be knocked down.这些旧房子将被拆除。The painting was
10、knocked down to Smith for 5 dollars.那幅画以5美元的价钱卖给史密斯先生了。The machines will be knocked down before being shipped to the Persian Gulf. 这些机器在运往波斯湾之前将被拆卸。He asked 500 for his car, but I managed to knock him down 10 percent.他的汽车要500美元，但我设法使他减价百分之十。knock out则主要表示下列几种意义：1.敲掉，敲空；2.在拳击中“击倒”对方，使其在规定时间内不能起立 3.比喻
11、用法：“使震惊，惊奇”。例如：He knocked the nail out.他把钉子敲了出来。He knocked his pipe out before refilling it.再装烟丝之前，他磕出了烟斗里的烟灰。Joe knocked his opponent out in the first round of the contest. 乔在比赛的第一回合中就把对方击倒了。 For a moment he was completely knocked out by the news of his friends death. 他被他朋友逝世的消息一下子惊得完全呆住。7、know, kn
12、ow ofknow作及物动词，表示“知道，懂得”的意思时，其后一般接表示事物的名词，从句，不定式复合结构。但它表示“认识，了解，熟悉”的意思时，其后多接表示人的名词或代词，也可接事物名词。例如：Do you know their names? 你知道他们的名字吗？Do you know what his name is? 你知道他叫什么名字吗？I never knew him to act without thinking.我从未发现他轻率行事过。I got to know him in the autumn of 1963. 我是在1963年秋天认识他的。know of亦可解作know ab
13、out，其后可接表示人或事物的名词，表示“知道（有），听说”的意思，指间接地获得的信息或情况，相当于hear of。例如：How did you come to know of this? 你怎么知道有这事的？I dont know him but I know of him. 我不认识他，但听说过他。8、known to, known for, known as这三个形容词短语在使用中均与联系动词be连用，只是在意义上有所不同。known to表示“为.所熟知”或“闻名于”等意，值得注意的是，在由及物动词know的主动句变被动句时，就要用这种结构。例如：The use of gunpowder was known to the Chinese before the Europeans.中国人懂得应用火药是在欧洲人之前。Luxun is known to the world. 鲁迅举世闻名。known for和known as的意义和用法与famous for和famous as相同。如：Hangzhou is known for the West Lake.杭州以西湖而闻名。He is known as a painter. 他以作为一名画家而出名。