The reason he was absent was he was ill and unable to go to school.
A. which; that
B. why; because
C. which; because
D. why; that
网友回答
A. which; that
B. why; because
C. which; because
(答案→)D. why; that
解析：第一空the reason是先行词，在定语从句he was absent中作原因状语，故用why；第二空是表语从句，陈述原因的内容，而且表语从句是一个完整的句子，故用that，其不作成分，没有意思，只起连接作用。句意：他缺席的原因是他病了，不能上学了。