we must do house___ and keep the windows____

we must do house___ and keep the windows____ We must keep quiet and walk___out of the room A. we must put rubbish bins and keep the environment We must do a lot of work to keep our environment clean and t we must keep the ( )on the road we must keep the( ) on the road we must s______ the earth and keep it clean and beautiful We must keep the classroom tidy and _________all the time.A. And we must keep careful of the rise in population at the sa we must keep the balance of ( ).(自然界) we must keep( ) in the hospital We must ___(keep) the classroom clean.