大学英语四级语法知识点及专项练习

1、大学英语四级语法知识点及专项练习虚拟语气虚拟语气是动词的一种特殊形式，用来表达说话人的意愿、请求、设想等未能或不可能实现的事实，或说话人看来实现可能性很小的情况。虚拟语气主要分为以下几类：1.主语从句中的虚拟语气主语从句中的虚拟语气主要取决于某些形容词和过去分词，用来表示建议、命令、要求、惊异和失望等。其形式为：（should）+动词原形。常这样用的形容词有：appropriate, advisable, better, desirable, essential, imperative, important, insistent, natural,necessary, preferable, strange, urgent, vital 等。过去分词有：desired, demanded, ordered, requested, suggested, recommended, required 等。例：It is essential that you attend all the meetings.你务必要参加所有的会议。It is suggested that the air con

2、ditioner (should) be fixed/installed by the window.空调要安装在窗户旁。2.表语从句和同位语从句中的虚拟语气在表示建议、命令、主张、目的和愿望等名词后面的表语从句和同位语从句中谓语动词要求使用虚拟语气。其形式为：（should）+动词原形。常这样用的名词有：resolution, pray, decision, motion, suggestion, preference, proposal, advice, recommendation,desire, demand, requirement, order, necessity, request, idea 等。例：My suggestion is that we leave the burning building at once.我的建议是我们马上离开燃烧的楼房。He put forward a proposal that we (should) all go for a picnic.他提议我们都去野餐。3.宾语从句中的虚拟语气(1)某些动词后所接宾语从句中的谓语动词要求用虚拟语

3、气，用来表示建议、命令和要求等。其形式为：（should）+动词原形。常这样用的动词有：ask, advise, determine, decide, command, insist, intend, move, prefer, propose, order, recommend, request, require, suggest, urge, demand, desire, direct 等。例：Some experts recommend that people set strict limits on their time for Internet use.许多专家建议人们严格限制自己的上网时间。We all insist that we should not rest until we finish the work.大家都坚决要求不完工不休息。(2)在以 it 为形式宾语的复合宾语从句中也可以用虚拟语气，其形式为：（should）+动词原形。这一句型中使用的形容词（宾补）与主语从句中的虚拟语气所使用的形容词相同。(3)wish 后面所跟的宾语从句中的虚拟语气表示某种不能实现

4、的愿望：表示对现在情况的虚拟：wish+主语+动词过去式或 were；表示对过去情况的虚拟：wish+主语+had+过去分词，或 wish+主语+would（could）+have+过去分词；表示对将来情况的虚拟：wish+主语+would+动词原形。例：I wish I were a child.我希望自己是个小孩子。I wish you had spent the wonderful evening with us last night.我真希望你昨天跟我们一起度过了美好的夜晚。I wish it would rain tomorrow.我希望明天下雨。4.if 条件句中的虚拟语气用 if 引导的非真实条件句是虚拟语气最基本的表现形式，它是由非真实的条件从句和与之相关的假设结果（主句）两部分组成，表达的是某种不存在的条件和假设下可能发生的事。按时间概念的不同可分为 3 种形式：与现在事实相反；与过去事实相反；与将来事实相反。这三种非真实条件句的动词表现形式通常来说是非常规范的，如下：例：If I were you, I would take a moderate stance to

5、wards your brothers affairs.要是我是你，我就会对你弟弟的事件采取温和的姿态。If I had known this beforehand, I would not have gone back.要是早知道这件事我就不回去了。If it were to rain, we would have to cancel the match tomorrow.假如下雨，我们只好取消明天的比赛。此外，用 if 引导的条件句在书面语中常把 if 省略而将were, had, should 放在主语前面，这种句型与 if 引导的条件句在要表达的意义上没有任何区别。5.以 as though 和 as if 引导的方式状语从句或表语从句中的虚拟语气as though 和 as if 意义相同，但 as if 较为常用。as if 引导从句使用虚拟语气时的从句动词形式分三种情况， 如下表所示。例：I feel as if I were ten years younger.我感觉自己年轻了十岁。The two strangers talked as if they had been

6、 friends for years.这两个陌生人交谈好像多年的朋友一样。It looks as if it might rain.看上去好像要下雨了。6.混合式虚拟语气混合式的虚拟语气，条件从句表示与过去事实相反，主句则表示与现在事实相反。结构如下表所示：例：If he had worked harder when young, he would be well off now.如果他年轻时多努力一点，现在就能过得舒服些。【专项训练】1Things might have been much worse if the mother （坚持她的权力）to keep the baby. 2The professor required that （我们交研究报告）.3If I （在学校更努力学习）, I would be sitting in a comfortable office now. 4We are all for your proposal that （讨论应推迟）.5I would rather have a room of my own, however small it i

7、s, than （与他人共用一个房间）.6The victim （本来有机会活下来）if he had been taken to hospital in time.7I lost your address, otherwise (or) I （很久之前就拜访你了）.8Since his injury was serious, the doctor suggested that （他不要参加比赛）.9I was afraid to open the door lest that （以免乞丐跟着我）.10We prefer that （该计划被充分讨论）before being put into execution.11I wont see you off at the airport tomorrow, so I will （现在祝你旅途愉快）. 12Give me your telephone number （我也许会需要你的帮助）.13Victor obviously doesnt know whats happened, otherwise （他不会做出这么愚蠢的评论的）. 14

8、You would not have failed if you （按照我的指令去做）.15Those flowers looked as if （好长时间没有浇水了）.参考答案及解析1答案 had insisted on her right解析 条件句主句为 might have done 的形式，表示与过去事实相反，所以从句应该为 had+过去分词的形式；“坚持某事”的常用表达为 insist on sth.。2答案 we (should) hand in our/the research report(s)解析require 后面接宾语从句时，从句中的谓语动词要用虚拟语气，即用 should +动词原形结构，should 可省略；表示“上交”用 hand in。3答案 had worked harder at school解析 这是一个错综虚拟条件句，从句是说“要是我在学校时（过去）努力学习了，那么我现在就会坐在舒服的办公室里”，对过去情形的虚拟，要用过去完成式，即 if I had worked harder at school。4答案 the discussion be pu

9、t off解析 表示建议的名词 proposal 后面的同位语从句要用虚拟语气，其谓语构成形式是 should+动词原形， should 可以省略；“推迟”的习惯说法是 put off。5答案 share a room with someone else解析 would rather do sth. than do sth.意为“宁愿做某事而不愿做某事”；“与某人分享某物”译为 share sth. with sb.。6答案 would have had a chance to survive/would have survived。解析 条件从句为 had+过去分词，表示与过去的事实相反，则主句用 would have+过去分词；“活下来”用 survive 表示。7答案 would have visited you long before解析 otherwise 表达的是含蓄条件，相当于 if 条件句，由时间状语“很久之前”可知，此处表达的是与过去事实相反的虚拟假设即相当于 if I had not lost you address，所以其构成形式为 would + have + done。8答案 he not participate in the game解析 表示建议的suggest 后面的宾语从句要用虚拟语气，其构成形式为 should+动词原形，should 可以省略；“参加比赛”可以表达为 take part in/participate in the match。9答案 the beggar should follow me解析 le

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