.The two boys are alike in age, but _____ they are as different as day and night.
______ at the news that his eyes rained tears.
—Has your former classmate come back from America?—Yes, he _____ there for 8 years.
—Hello, can I speak to Mr. Smith?—I’m sorry, but it is 3 weeks _____ he worked here.
—It’s hard to believe that Jack should have fought with the policeman.—Yes. If one ____ ask for trouble, it can’t be helped.
—When did your brother begin to show his interest in medicine.—It was a Saturday _____ he noticed his classmate experimenting on a frog in the lab.