七、it的用法
1.指代一个人或事物。
It's only a fifteen-minute ride to my school.
It often rains in the south of China.
"Who's that?" "It's Liming."
It's early spring.
2.作句子的形式主语，代替不定式、动名词或从句。
It took me five minutes to finish reading the exercise.
It cost me five yuan to buy the pen.
The color TV set costs me more than 2,000 yuan.
I spent ten hours in finishing the work.
I spent twenty yuan on the shirt.
It is no use crying now. You'd better study hard now.(it is no use doing sth. )
To his surprise, it turned out that Tom failed the entrance examination.(to one's surprise 使某人感到惊奇)
It's a pity that you didn't watch the match.
It is necessary for us to have some exercise every day.
3.作句子的形式宾语，代替不定式、动名词或从句。
They all regard it their duty to help the poor people.
I don't think it worthwhile taking so much trouble.(It's worthwhile doing. 做……事是值得的)
We find it difficult to learn English without practicing.
I think it no use telling them.
I don't think it very important that we should take part in the discussion.(take part in 参加)
He feels it his duty to help others.
4.构成强调句型。当强调的部分是主语，并且主语是人时，句型中的that 也可以换作who。
强调句基本构成 it is that…
It is in the room that we met each other for the first time.
It was not until 1936 that basketball became a part of the Olympic Games.(not until 直到……才)
It was they who attended the meeting last week.
It is because the book is so useful for my work that I bought it.
考试重点
that和those有时分别用来代表前面提到的不可数名词和名词复数，以避免重复。而可数名词单数往往用the one 或that one 来代替。that 可以指上面提到的事情，this指下面要谈的事情。
不定代词中，both 放在实意动词前，系动词be 的后面。every只能跟名词，each可以跟名词也可以不跟名词。every在代词部分要出现当每隔……讲。
few, a few, many 修饰或指代可数名词，little, a little, much修饰或指代不可数名词。few, little表示否定。
one the other，some others，the others
it用法重点就是强调句。it作为形式宾语时不接is。
代词部分的难点之一是名词型物主代词与形容词型物主代词的区别。顾名思义，形容词型物主代词起的是形容词的作用，在句子中只能作定语，名词型物主代词起的是名词的作用，代替上文出现的名词，在句子中一般作主语、宾语、表语等。
Let's clean their room first and ______ later.
A. our B. us C. we D. ours
(答案为D，ours 相当于our room。)
代词部分的主要考核点是不定代词。如some, any, few, a few, little, a little, many, much, one, none, all, both, either, neither, each, every, other, another, 以及some, any, no, every 与body, one, thing 构成的合成代词。
(1)泛指与特指。如：another, other, others 是泛指，the other, the others是特指。
(2)肯定与否定。如：a few, a little, either, some 及其合成代词表示肯定，few, little, none, neither, any 及其合成代词表示否定。
(3)可数与不可数。如：few, a few, many, one 修饰或指代可数名词，little, a little, much修饰或指代不可数名词。
代词部分的另一个考核点是it。
it 可以代替上文出现的单数事物。
The picture was changed while drawn from memory as it passed through the class. (it 指代the picture。)
it takes sb. some time to do sth. 花费某人多长时间做某事
It takes half an hour or so to walk to the bus stop.
He made it plain that he was annoyed with me.
it 还可以构成强调句型，即"It is / was +被强调的部分+ that …"。当强调的部分是人，并且是主语时，that可以换成who。强调句去掉it is / was 与that即成为普通的句子。
It was last night that I saw you in the restaurant.
It was she who / that suggested that he go to New York in order to get a direct flight.
