问题补充：
That was the only gate we could rush out and save those were in great danger.
A. that; which
B. which; who
C. through which; who
D. at which; who
答案：
A. that; which
B. which; who
(答案→)C. through which; who
D. at which; who
解析：考查介词+关系代词的用法。本句意思是“这是唯一一扇通过它我们能冲出去的门，救那些处境极其危险的人”。
