问题补充：
food is hard to find, few birds remain throughout the year.
A. What
B. Which
C. Where
D. That
答案：
A. What
B. Which
(答案→)C. Where
D. That
解析：考查从句，句子food is hard to find不缺少成份，所以只能在关系副词里找，What、Which That引导从句时，可以充当句子成份，可以做主语、宾语等，所以选C，句子意思“那里的食物很难找，经过一年很少的鸟留下”。
