问题补充：
The Hengxin Square is located in used to be our canteen.
A. what
B. where
C. which
D. the place
答案：
(答案→)A. what
B. where
C. which
D. the place
解析：：考查宾语从句。What引导宾语从句what used to be our canteen并在句中做主语。Where是副词，不能在句中做主语。The place后面缺少关系词。句意：恒心广场位于过去是我们的餐厅的地方。故A正确。
