His ideas of socialism were in advance of the times ,_____ made him an enemy of the capitalisticgoverment.此控填WHICH 为什么不能用what

His ideas of socialism were in advance of the times ,_____ made him an enemy of the capitalistic
goverment.此控填WHICH 为什么不能用what

非限定性定语从句,which指代前面的一句话.what不能用作定语从句中的关系词.