_______, he is invited to make a speech on how
to deal with the relationship between boys and
girls.
A.Previously arranged
B.Having been previouslyarranged
C.As previously arranged
D.arranging
答案给的C，是原因状语吗？A与B为什么不选？

答案给的是正确的。
用AS引导的原因其实很简单，句子_______, he is invited to make a speech on how
to deal with the relationship between boys and
girls.中的主语是HE，但是逗号前的空格显然意思应该是“他去演讲这件事情被事先安排好了，”而不是主语HE被事先安排好。所以A和B都不对，如果选他们，那么就成为对主语HE的一个补充说明，意思上就完全错误了。
对于这种题目，你首先要看句子的主语是什么，然后判断意思，最后判断时态。