They use computers to keep the traffic smoothly.
Please put all the magazines _______ on the shelf after you finish reading them.
While copying this paper, be careful not to ______ any words.
You can borrow my car ________ you promise not to drive too fast.
--- Could you turn the TVdown a little bit? --- ________. Is it disturbing you?
Without your timely help, we ________ in big trouble that day.