1．重点单词：litter，bottom，fisherman，coal，ugly，advantage，cost，wooden，plastic，takeaway，bin
2．重点短语：the bottom of，play a part in，make a difference，cut down，lead to
3．重点句式：
We're trying to save the earth.
Even the bottom of the river was full of rubbish.
Everyone in this town should play a part in cleaning it up.
I used to be able to see stars in the sky.
So together，our actions can make a difference and lead to a better future.
