问题补充:
Some people fear that air pollution may bring about changes in weather around the world.
A. /; the
B. the; /
C. an; the
D. the; a
答案:
A. /; the
B. the; /
C. an; the
D. the; a
解析: Air pollution 是抽象名词这里是泛指,weather 这里是特指全球的气候,根据the weather around the world 可知。