Smiling doesn't mean you're happy. Sometimes, it just means that you're strong enough to face problems.
—Tom is so worried about the test that he said he was going to study all night. —Tell him he should quit ______ and get some help.
John didn’t feel well yesterday; otherwise he ______ to see his friend off at the airport.
_____ you are familiar with the author’s ideas, try reading all the sections as quickly as you possibly can.
Before the first nonstop flight made in 1949, it_____ necessary for all planes to land for refueling.
Students who pass the test will be ______ to the next grade, as has been announced.