I want to teach in Tibet when I graduate from the college. — Me too. Teachers （ ） very much there.
（A）need
（B）are needing
（C）are needed
（D）needed
We will go camping if it （ ） tomorrow.
（A）don't rain
（B）didn't rain
（C）doesn't rain
（D）isn't rain
Up to now, our society （ ） with limited living space and a shortage of natural resources.
（A）has been challenged
（B）is being challenged
（C）is challenging
（D）has challenged
