Compared with 2 million tons last year, our coal output has increased _____three times; that is to say, our coal output has increased_____8 million tonsthis year.
That was the last time I saw my father before he _____.
The experiment __ to be .
Many _______ of years later, the first extremely small plants began to appear on the surface of the water.
As a child, Franc _____.
They won’t buy any new clothes because they ________ money to buy a new car.