—Hi, Tom, why are you looking so tired?—I'm tried. Because I ______ the living room all day.
As long as you stick to it,you’ll make progress ________.
The two balls fell ________the same speed and landed ________the ground at the same time.
After many years of hard work,Mary and her husband had at last paid ________all the money they had borrowed.
They thought the meeting was ________great importance.
________the birthrate down by 10%,the number of the population has decreased.