A society cannot be successful if it throws tradition away, but it cannot be successful ____if we do something to stop progress.
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.
When choosing a product, I sometimes try to figure out the meaning___ to its brand name.
There is hardly an environment on earth ______ some species of animal or other have not adapted successfully.
—I don’t feel like going out. Why don’t we just stay home and watch TV instead? — ______ You promised to take me out for dinner and to the theatre on my birthday.