— is the population of America?—I don’t know. But I know it’s than that of China.A. What

问题补充：

— is the population of America?

—I don’t know. But I know it’s than that of China.

A. What; smaller B. How much; smaller C. What; less

答案：

解析：句意：美国的人口是多少？我不知道，但我知道比中国人口少。Population人口，名词，用what对其提问；small小，用来形容人口数字的大小，而不用little；这里用small的比较级smaller，故选A。