New words：

vital [ˈvaɪtl] adj.必不可少的；至关重要的

Sample Sentences：

Water is vital for all living things.​
The police play a vital role in our society.
A sparrow may be small but it has all the vital organs.

organ [ˈɔrɡən] n.机关；风琴；管风琴；（人体或动植物的）器官

New words：

composition [ˌkɒmpəˈzɪʃ(ə)n] n.成分；作文；构成；作品

Sample Sentences：

Scientists are studying the composition of the air in big cities.
We have to write a composition about our dreams every month.
They analyzed the composition of the medicine to see if it was safe.
The famous musician is good at composition and has created many wonderful songs.

New words：

composite [ˈkɒmpəzɪt]
n.复合材料；混合物；合成物
adj.合成的；混成的；复合的

Sample Sentences：

The car’s body uses advanced composite.
The boy's character was a composite of his parents.

The composite material is light but strong.
Composite paint dries faster and lasts longer than ordinary paint.

New words：

component [kəmˈpoʊnənt] n.成分；部件；组成部分

Sample Sentences：

There are many components to the machine.
Trust is a vital component in any relationship.
Each component of the model plane must be put together carefully.

vital [ˈvaɪt(ə)l] adj.必不可少的；至关重要的

New words：

composer [kəmˈpoʊzər] n.作曲家；创作者；作曲者

Sample Sentences：

Who is the composer of the song?
He was born to be a great composer.