Li Lei hasn't come yet. I don't know what ________ to him. [ ]

A. is happened

B. has been taken place

C. has taken place

D. has happened

下列关于价格鉴证结论书的撰写要求，错误的是（）。

A.通过分析要点得出关键结论

B.数据准确可靠

C.文字简练、层次清楚

D.融会贯通、结论明确