1. 当主语为reason 时，表语从句的连接词要用that，不用because，构成句型“the reason (why…) is that….”    The reason why you did not join us seems unbelievable.2. A is to B what C is to D.    English is to me what fish is to water.3.在一些表示“建议、劝说、命令”的名词后面的表语从句中，谓语动词用虚拟语气。should+动词原形表示，should可省略。如：    My suggestion is that we (should) start early tomorrow. 我的建议是我们明天一早就出发4.系动词分类：一、根据系动词后所跟结构，我们可以把英语系动词分为两大类：     完全系动词（其后只能跟表语的动词，如be, seem）和半系动词（其后既可跟表语作系动词用法，也可跟宾语或状语作实义动词用，如look）例如：   1）He looked sadly at the boy.(“看着”，实义动词用法)        He looks a clever boy .（“看起来”，系动词用法）   2）He looks at a clever boy.（“看着”，实义动词用法）在英语中，某一动词是多义词，既有实义动词用法，又有系动词用法。二、根据系动词的意义，我们把英语系动词分为四类：A．五大感官系动词  B．状态系动词  C．动态系动词  D．双谓语系动词1．look“看起来像是”，后接adj.、n.、分词、介词短语、不定式等。    The girl bit her lips and looked thoughtful.这位女孩咬着嘴唇，看上去若有所思。2．smell“闻起来”，后接adj.分词。    The flowers smell sweet. 这些花气味真香。3．sound“听起来”，后接adj.分词。    The music sounds sweet.这首诗听起来真悦耳。4．taste“尝起来”，后接adj.分词。    The apples taste very good. 这些苹果很好吃。5．Feel ①“摸起来，给……感觉”；②“觉得”，后接adj./p.p.    You will feel better after a night’s sleep. 睡上一晚，你会觉得好些。3．appear,“显得，看起来好像”，半系动词。    It appeared(to be)a true story.看来这是一个真实的故事。4．keep, “保持……的状态”，半系动词，后接adj或介词短语。    You’d better go to bed and keep warm. 你最好躺在床上去暖和一下。5．remain,“仍是”，半系动词。    I remained silent. 我仍然缄默。6．stay“保持（某种状态）”，半系动词，后接adj.、过去分词。    The window stayed open all the night.7.prove “证明是”，半系动词，后接adj. .    The treatment proved to be successful. 这种疗法证明是成功的。1．get“变成，变得……起来”，后可接形容词、分词、介词短语。    The days are getting longer and longer. 白天变得越来越长了。2．fall“进入（某种状态），成为”，后常接以下形容词：asleep, lame, silent, ill, sick, flat.    The old men, unable to express himself, fell silent. 那位老人说不清自己的意思，就不做声了。    My father fell ill and died. 我的父亲生病死了。3．grow“渐渐变得……起来，长得”    It’s growing warm. 天气渐渐暖和起来了。4．turn“转变成（新的与原来完全不同的色彩或性质），变质（色）”。    Maple trees turn red in autumn. 枫叶在秋天变红了。    It was cloudy this morning, but fortunately it has turned fine.今天早上是阴天，幸好已经转晴了。5．go，“变成（某种坏的状态）”   The telephone has gone dead. 电话不通了。   The material has gone a funny colour. 这料子的颜色变得奇怪了。 go之后常接的adj. 还有：bad, blind, wild, wrong, sour, hard, hungry, mad, red, with, anger, white, pale, blue, grey.6．become“变成，成为（好坏均可的情况）”    I became interested in drawing. 我开始对素描感兴趣了。    He became angry with me. 他对我生气了。    They became good friends. 他们成了好朋友。7．come，“变成为（已知的状态），证实为”，后常接形容词或前缀un-的过去分词作表语，表示状态或情况的变化。    His wish to become a pilot has come true. 他想当飞行员的愿望实现了。     If you look into the matter, everything will come clear.如果你调查一下这事，一切都会清楚。后面常接的形容词还有：apart, dear（昂贵），natural, open, short, right（好了），unstuck（没有粘住），untied（松开）。8．run,“变成”，后接adj.    The price ran high. 价格上升了。9．make，“达到某种状态[后接形容词]，如sure, certain, merry, bold, free    We must make certain of facts.我们一定要弄清事实。D．双谓语系动词 此类系动词既有系动词的功能，后接表语，又保留原实义动词本身的含义。例如：The run rose red.太阳升起红艳艳。        She stopped and stood quite still.她停下来然后一丝不动地站着。        The snow lay thick on the ground. 雪厚厚地堆积在地上。        He married young. 他结婚很早。        Lei Feng died young.雷锋早逝。        He continued silent.他继续沉默不语。