The reason she can finish the homework ahead of time is she is both clever and hard-working.
A. why;why
B. why;that
C. that;because
D. for;because
网友回答
A. why;why
(答案→)B. why;that
C. that;because
D. for;because
解析：第一个空为why引导的定语从句，第二个空为由 that引导的表语从句，that在从句中不充当任何句子成分。