The present question is ____ many students consider itimpossible ____ is really possible if effort is made.

No one knows how the huge rocks _______ and _______ without our modern machines eight hundred years ago.

It took people three months to build this great building.

This cake is ________ that one. Which of the following is wrong?

Thank God we’ve finally cleared up some problems. Let’s ______, shall we?——All right. See you tomorrow.