1.at the bottom of the river 在河的底部
2. be full of the rubbish 充满了垃圾
3. throw litter into the river 把垃圾扔入河中
4. play a part in 尽一份力...
6.cut down air pollution 减少空气污染
7. make a difference 产生影响
11. use public transportation 使用公共交通
12. recycle books and paper 回收书和废纸
13. use paper napkins 使用纸巾
14. turn off the shower 关掉喷头
15. fill the air with black smoke 使空气中充满了黑烟