that, it, one的用法

　　● that, it, one的用法

　　⑴ one 可指人或物，具有"泛指"性质，替代可数名词；that 只指物，可替代可数或不可数名词，具有"特指"的性质。

　　There were two boys there. They chose the strong one.

　　那里有两个男孩，他们挑选了身体好的。

　　The new designs are much better than the old ones.

　　新的图案比旧的好多了。

　　The study of idioms is as important as that of grammar.

　　学习惯用法与学习语法同等重要。

　　⑵ one 和 that 在替代可数名词时， 如果没有前置定语，只有后置定语，两种可以互换， the one常用于口语，that 主要用于正式文体。 但该名词前有前置定语，则只能用 one.

　　I'll take the seat next to the one(=that)by the window.我坐在窗口的那个座位旁边。

　　I prefer the large box to the small one.我喜欢这个大盒子胜过那个小的。

　　⑶that 的复数 those 代替可数名词的复数。those 可指人或物，一般后接修饰语。

　　Today's computers are of much greater difference from those(=the ones)used in the past.

　　今天的计算机和以前的大不相同。

　　The clothes people wear today do not seem to last as long as those of my father's day.

　　当今人们所穿的衣服似乎不如我父亲那时的耐穿。（后有of短语，不可与the ones换用）

　　⑷ one 和 it 都可以用来指代某种东西。one 是指不定的东西； it 指特定的东西。

　　I have lost my umbrella, I think I must buy one again.

　　我的伞丢失了， 我想我得再买一把来。

　　My father bought a bike and gave it to me.

　　我父亲买了一辆自行车，把它给我了。

　　⑸ it用来作形式主语，形式宾语，代替不定式，动名词，从句。也可指距离，天气，时间等。

　　"They were all going to return the same night." "Well,they did intend it."(代替不定式)."他们都准备在同一晚上返回。" "对，他们的确有这种打算。"

　　I consider it important to ask him for advice.

　　我认为征求他的建议很重要。

　　We found it useless learning a theory without practice.

　　我们认为学习理论而没有实践是没用的。

　　May I take it that you will write me a letter?

　　我可以相信你会给我写信吧？