用所给词的正确形式填空。
【小题1】We should stop _________ (throw) rubbish into rivers.
【小题2】In the past, the Earth _________ (be) clean and beautiful.
【小题3】My brother is __________ (plant) trees in the backyard.
【小题4】The Earth __________(get) sick now.
【小题5】We shouldn’t __________ (cut) down so many trees.

The sun is _______. I am going to fly a kite in the park. （ ）

A．shine

B．shines

C．shining

He’s __________________ an e-mail. (   )

A．writing

B．write

C．written

—Where are they? —They are in the classroom. They are _____.

A．playing game.	B．play a game
C．Lily and Mike	D．a tree

What _____you  doing ? (    )

A．do

B．is

C．are