问题补充：
At a rough estimate, our school is their school.
A. three times as the size as
B. three times size of
C. three times the size of
D. three times as the size of
答案：
A. three times as the size as
B. three times size of
(答案→)C. three times the size of
D. three times as the size of
解析：考查倍数表达。倍数表达的基本结构：
1. “A+倍数+形容词或副词的比较级+than+B”，表示“A比B大（长、高、宽等）多少倍”。
2.“A+倍数+as+形容词或副词的原级+as+B”，表示“A正好是B的多少倍”。
3. “A+倍数+the size/height/length/width， etc+of+B”，表示“A正好是B的多少倍”。
4. “……times+what+从句”。
句意：大概估计，我们学校是他们学校面积的三倍。故选C。
