注意：在用于被动语态时，以上三个短语中的from都不能省略。

【相关链接】

(from不省略)

7.purify vt. 使纯净；净化；提炼

【典型例句】

Water is purified by passing through rock.

水在穿透岩石的过程中得到了净化。

The soil has to be purified of all bacteria.

要消灭这土壤的所有细菌使之净化。

Hindus purify themselves by bathing in the Ganges.

印度教徒在恒河中浸泡借以涤罪。

【相关链接】

pure adj. 纯的；纯净的；干净的

I want a bottle of pure water.

我想要一瓶纯净水。

They met by pure chance.

他们相遇纯属偶然。

pure gold 纯金

purely adv. 仅仅；完全

She took the job purely and simply for the money.

她做这份工作图的就是钱。

8.quantity n. 数量；大量；大批

【典型例句】

The data is limited in both quality and quantity.

这份资料在质量和数量上都很有限。

The police found a quantity of drugs at his home.

警察在他家发现了大量毒品。

It's cheaper to buy goods in quantity.

大量购物比较便宜。

What quantity do you require?

你要求多大的数量？

I prefer quality to quantity.

我重质不重量。

There is only a small quantity left.

只剩下很少。

【知识小结】

（1）in large quantities 大量地

（2）a large quantity of 修饰名词作主语；谓语动词用单数；quantities of 修饰名词作主语，谓语动词用复数。

【相关链接】