问题补充：
Though I have no idea the new film is about, I know it is popular with all who have seen it.
A. whether
B. why
C. that
D. what
答案：
A. whether
B. why
C. that
(答案→)D. what
解析：本题考查同位语从句。从句中about是介词后没有宾语，故应选择作宾语的引导词，所以选D。what引导名词性从句在句中可作主语、宾语、定语或表语。
