替代词one, ones, that, those, it, this, that1)one, ones, that, those That替换单数可数名词或不可数名词；one只替换 单数的可数名词。Eg: The vase on the left is more beautiful than _ on the right. The coffee produced in Brazil is more famous than _in Mexico.the onethatThat只用于替换表示事物的名词， 而one/ones替换 表示人和表示事物的名词皆可。Eg: His younger sister is taller than the elder _.I need the plastic bags, not the paper_ .oneonesThat/ those一般不带前置定语，但必须有后置定语 。One/ones都可。当替换词的后置定语用所有格的 of短语或当替换词被所有格修饰时，不用one/ones 而用that of/those of.Eg: I like the vase better than _in another shop.The windows of your flat are cleaner than _of mine.A grandparents job is easier than _of a parent. The computers in our school are connected to the Internet while _ in their school arent.the one / thatthosethatthoseThat/ those用于替换有定冠词的名词；one/ones用 于替换有不定冠词的名词。Eg: The style of the building is similar to _of a temple.A CD player made in Japan costs more than _made in China.thatone2) it, this和 that都可以替代前文已提到的事或情况，细微差别在于 it不如其余两者那么强调。Eg: So she decided to paint the door pink. _upset the neighbours a bit. So she decided to paint the house pink. _really upset the neighbours.It That当前面提到的事物不止一件时， it通常指最先提到 的事物，而this/that是指最后提到的事物。 Eg: We keep the ice cream machine in the spare room. _is mainly used by the children. (指 the machine)We keep the ice cream machine in the spare room. _is mainly used by the children. (指the spare room)ItThis/ThatThis可以出现在它所指代的事物之前；而that 则指上文所提到的事物。Eg: Listen to_! We will have three days off. “A penny saved is a penny earned.” Who said_?thisthatEg: I bought a dictionary three years ago and I am still using_ now. I bought a dictionary three years ago but I am going to buy a new _soon.It用以指特定的前面提到过的事物，即：it和它替 换的是同一个事物，it前无修饰语；而one用于替 换与前提事物有共同之处但并不完全一样的事物， 因此，one之前或之后一定有修饰语来加以区别。3) It和oneitoneIt引起的几个易混淆的时间句型 It + be + 时间 + since-clause 这个句型表示从since 从句谓语动作发生以后到现在或过去所经过的一段 时间，意为“自从.以来已多久了” It is three years since his father passed away . It + be + 时间 + before-clause 这个句型中的时间一般为表示一段时间的词语 (如：a long time , months , weeks , days ,hours , minutes ) ，主句中的谓语动词用肯定式，意为“ 过多长时间才.”。主句的谓语动词是否定式时 ，意为“没过多长时间就.”。主句的时态可用 过去时was或将来时will be；用was 时，before从句 的动词用一般过去时；用will be 时，before从句常 用一般现在时。 她没过多久就背会了那些诗歌。 It was _she learned those poems by heart . 过了很久警察才来。 It was _the police arrived . 要过好几个小时他才会作出决定。It _hours before he makes a decision . 要不了几个小时我们还会再见面的。 _before meet again . not long beforelong beforewill beIt will not be hours3. It + be + 时间 + when-clause 这个句型中, it 指时间，而且表示时间的词语前 没有介词(时间一般为具体时间)。主句中的谓语 动词和从句中的谓语动词在时态上一般是一致的 ，主句是will be，when从句用一般现在时代替将 来时。 It was already 8 oclock when we got home . It was the next morning when we finished our work . It will be midnight when they get there . It + be + 时间 + that-clause 这个句型是个强调 句型。例如：It was two years ago that he made an important invention . (原句是： _) It was at 5 oclock that he practised playing the violin in the morning . (原句是： _) 比较：It was 5 oclock when he started in the morning . (5 oclock前没有介词，这是个定语从 句) He made an important invention two years ago . He practised playing the violin at 5 oclock in the morning . It + be + time + that-clause 这个句型属虚拟语气结构，不管主句中用的是 is 或 was ，that从句都须用动词的过去式或should + 动词原型(但不及用过去式普通)，在time之前有时 可加上high或about 以加强语气。例如： It is time(that)we handed in our exercises . (= It is time that we should hand in our exercises .) It is high time (that ) she wrote a letter to her boyfriend . It / This / That + the first(second , third ) time + that-clause 这个句型表示截止到说话时为止的某人的一种 经历，关键是注意time前有序数词，主句是 is 时 ，从句要用现在完成时；如果主句用一般过 去时was ，则从句须相应地用过去完成时。例 如： This is the first time (that) these Europeans _the Great Wall . It was the fifth time (that) I _a friendly visit to Africa . had paidhave visited There起始的句型归纳：1） there live/stand/lie/existThere lay a ditch two metres wide ahead. 2) There come/go/appear/occur/follow用于 描述某事的发生或某个动作的开始。Eg: There will follow a break of 10 minutes and then we will go on with the lecture. 3) There being（独立主格结构） Eg: There being nothing left in the fridge, we had to do some shopping first.4) there to be结构常见于动词intend, mean, consider, hate, want等词后。 Eg: No one would expect there to be a war in his country.I dont want there to be another accident like this. 结构：It+动词be+强调部分+who(whom)/that+ 其他部分it可以用来对句子的某一成分加以强 调。It 用于强调句Eg: Nancy saw your sister in Tokyo last week. It was Nancy who saw your sister in Tokyo last week. It was your sister whom Nancy saw in Tokyo last week. It was in Tokyo that Nancy saw your sister last week. It was last week that Nancy saw your sister in Tokyo.有些否定句也可以改成这种强调结构：It wasnt until last summer that I heard from her. I didnt do all this for myself. It wasnt for mysel