【题目】He is so stubborn that once he makes up his mind, nothing can change it, _______, it's no use arguing with him.
A.therefore
B.however
C.besides
D.so

【答案】A
【解析】考查连词辨析。therefore意为“因此”；however意为“然而”；besides意为“除了……还有”；so意为“所以”，句意：他是如此固执,一旦他决定,没有什么可以改变它,因此,与他争论是没有用的。根据句意可知选项A正确，故选A。