after which还是after what

After _______ had happened he could not continue to work there.

A. which                        B. how

C. what                          D. having

【分析】可能误选A。最佳答案选 C。有的同学误选A，是因为认为介词后应接关系代词 which，但实际上，若填关系代词，其前没有先行词，这根据不是一个定语从句。另外，由于 had happened 缺主语，所以B和D也不能选。请再做下面一题(答案选B)：

He pointed to ______ looked like a tomb and said, “Ghost.”

A. that                           B. what

C. which                        D. as