评论
打印
重点讲解：
1. be composed of 组成；构成；
All animals and plants are composed of cells.
一切动植物均由细胞组成。
2. concentrate on 全神贯注;集中（心思）；
I am leaving to concentrate on writing fiction.
我辞职是为了专心写小说。
3. hail from （人或物）来自；
They hail from all parts of the country.
他们来自全国各地。
4. be dependent on 取决（于…）的；有赖（于…）的；
Up to two million people there are dependent on food aid.
那里有多达200万人口依靠食品援助。
n. 植物学，植物
