( ) 1. I know your writing is _____________.
A. enjoying B. enjoy C. enjoyable D. to enjoy
( ) 2. We must be careful _______ the environment.
A. to B. about C. with D. at
( ) 3. It’s ________ to throw away glass and paper.
A. useful B. useless C. wasteful D. wasteless
( ) 4. There are ______ green school in China.
A. thousand B. thousands of C. thousands D. thousand of
( ) 5. We