Can it be in a fast-changing world we don’t know what to teach our children today?
A. which
B. that
C. why
D. since
网友回答
A. which
(答案→)B. that
C. why
D. since
解析：考查主语从句，该句陈述句为it can be that in a fast-changing world we don’t know what to teach our children today。It作形式主语。
句意为在一个快速发展的世界，我们不知道该教我们的孩子什么，这可能吗？