one 和it 用法区别简议

[狐狸大仙]

One用作代词，意为“一个（人或事物）”，用于代替表示单个的事物或人的名词、名词短语，通常是代替前面刚刚提到的一种可数的东西，
如：I want a photograph of you—would you give me one?
Do you have a camera? No, but my dad has one .
One还可替代前面表示类别即泛指的人或事物,也可替代前面特指的人或事物。
如：Can I borrow your shawl, the reddy-black one?
The problem is one that has caused us a lot of trouble.
而且，one不仅可替代前面单数的人或事物，其复数形式ones也可替代前面复数的人或事物。
如：She also has two grey shirts and three red ones.
There are only hard chocolates left; we’ve eaten all the soft ones.
It代词也可替代前面刚刚提到的事物，但他通常指前面所提到的具体的、同一事物或抽象的事物，即，替代特指的无生命物、植物、动物、经历、活动和抽象概念等。
如：I took a quick glance at the house and noticed it was very old.
She went up to the cat and started stroking it.
We promised to stand together, so we got to do it.
Do you have a computer? No, but my brother has one. He bought it last month.
此外，在不特殊考虑或性别不详时也可替代前面提到过的人或婴儿。
如：She was holding a baby in her arms and it was crying.

[◣落花隨水]

细小的知识点,但很有用~