Mr. Painter wanted to design a new system to ________ the water in his garden in heavy rains.

Where did you see your friend—It was in the super market ____ I was doing shopping

We should________the lights when we leave our classroom because we must save electricity. [ ]

No matter who you are and what are you, ________， we should remember that “being” and “doing” are much more important than “having”.[ ]

Is John coming by train? — He should, but he _____ not. He likes driving his car.[ ]