What would you do if you ________ on the moon?
Look! Some boys are playing baseball, ________ are chasing, they all have fun.
We have a lot of homework______. We are very busy today.
Where is your father?——He _______ Shanghai. He has ______ there for a week.
The environment is becoming worse and worse. I think we should do something to ____ people ____ cutting the trees in order to protect the earth.