22.　 We should plant more trees to make our city greener. The more trees, the better.

21.　 If everyone makes a contribution to protecting the environment, the world will become much more beautiful.

20.　 It is our duty to keep our environment clean and tidy.

19.　 Wherever you live, you can do something around your neighbo(u)rhood.

18.　 Taking care of our environment is very important.

17.　 It’s a pleasant way to help keep our environment clean and tidy.

16.　 Whenever some one throws in some rubbish, it produces a piece of music.

15.　 Do you thing Greener China can do something?

14.　 You give it your best shot.

13.　 His teacher, Mr. Feng, spoke highly of his student.