温经汤中配伍半夏的主要用意是（）.

A.燥湿化痰而和胃

B.和胃降逆而止呕

C.通降胃气而散结

D.降逆散结而消痞

E.化痰开胃而行津

He arrived on the day ______ there happened to be no plane tickets left for Shanghai.[ ]

A. on which  

B. for which  

C. with which  

D. by which