1、1.替代词 one, ones, that, those, it,this, that1)one, ones, that, thoseThat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 you
2、nger 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 grandpar
3、ents 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 _ma
4、de in China.thatoneEg: 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。2. It和 oneitoneIt引起的几个易混淆的时间句型 It + be + 时间
5、+ 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
6、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
7、 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-clau
8、se 这个句型是个强调句型。例如：It was two years ago that he made animportant 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
9、 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 ourexercises .) It is high time (that ) she wrote a letter to her boyfriend .
