4.play a part in=play a role in
参与；发挥作用；扮演角色
【例句】
Everyone will play a part in protecting the earth.The sea will be cleaner and the sky will be bluer.So the environment will get better and better.
【例句】
People usually play a role in deciding the winner.
in介词+doing
play an important part in doing sth.
在某方面发挥重要角色
【例句】
I don't believe that our environment will get better if nobody plays a part in saving it.
译文：如果没有人为保护环境出一份力，环境就不会变好。
Nobody 不定式作主语，动词用三单形式，Everyone也是
5.build v.建立；建造
【例句】
Chinese workers built （build）many tall building in some other countries in past.
build up 增强（体质）；加强；增大
more 更多的 many much 的比较级
修饰可数名词，也修饰不可数名词
little 比较级less 不可数
few 比较级 fewer 可数
解题思路，圈出被修饰的词，先判多少，再看可数或不可数
