4. 大多数人都熟悉这样一个概念，物质是由叫做原子的极小粒子组成的。
Most people are familiar with the idea that matter consists of very small particles called atoms.
5. 一星期由七天组成。
A week consist of seven days.
6. 混合物由两种或更多彼此不发生化学合成并能被分开的物质组成的合成物
A composition of two or more substances that are not chemically combined with each other and are capable of being separated.
7. 马氏本，马登斯体一种由铁和高达百分之一的.碳组成的溶液，是硬化碳工具钢的主要成分。
A solid solution of iron and up to 1 percent of carbon, the chief constituent of hardened carbon tool steels.
8. 鉴于税务原因，我们得组成公司。
We had to incorporate for a company for tax reasons.