—Sorry, I’m late for work.—Is that ________ you got stuck in a traffic jam again?
The traditional view is ____ we sleep because our brain is “programmed” to make us do so.
Then you usually lie there just ______ the ceiling, thinking about everything that could go wrong.
—What do you think of his opinion? —None has given me ___________ piece of advice.
The boy should be punished. You shouldn’t let him ______ cheating in the exam.
You can only be sure of _____ you have at present;you cannot be sure of something _____ you might get in the future.