The reason their failure you know is they didn’t get fully prepared for the experiment.
A. why; that
B. that; why
C. for; that
D. why; because
网友回答
A. why; that
B. that; why
(答案→)C. for; that
D. why; because
解析：考查介词及表语从句。“the reason for… is that…”是一个固定搭配。意为：．．．的原因是什么，for修饰the reason，that引导的表语从句，句意：他们失败的原因是他们没有充分准备好实验。因为the reason后面不是定语从句，不能用why。选Ｃ。