With the change of the economic foundation the entire immense superstructure is _____ rapidly transformed.

The question that puzzled them is ____ they can get rid of the air pollution in the area.

It will cost a lot of time. __________I think we shallneed it and it will certainly be useful to us more or less.

Could you _____________ watch TV. I’m sleeping.

More and more trees were cut down. _____, many animals are dying out.