问题补充：
What should the people do to solve the food problem if they live in hilly areas is hard to grow
crops?
A. where
B. when it
C. that
D. where it
答案：
A. where
B. when it
C. that
(答案→)D. where it
解析：主要测试定语从句。所选项应是定语从句中的关系副词, 地点状语, 而且从句中又缺乏形式主语,故选D.
