________ is know to us all is that the old worker, for _______ life was hard in the past, still works hard in his seventies.
The mother asked her son________.
After the examination,my teacher told me that failure _______the mother of success.
He told us he _______a concert________.
—I’d love to make friends with the boy ____ you think is easy to _____. —OK. I’ll introduce you to him at the party.
I soon found that the work I was doing ____ by someone else — in other words, I was wasting my time.