caused the accident is still a complete mystery.A. What B. That C. How D. Where

发布时间：2020-08-17 13:45:15

     caused the accident is still a plete mystery.
A. What
B. That
C. How
D. Where

网友回答

(答案→)A. What
B. That
C. How
D. Where
解析：此题考查what引导名词性从句作主语。
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