桂枝汤中桂芍配伍的意义是：
A．解肌祛风，疏通营阴
B．温通卫阳，发散表邪
C．温通阳气，和营而止痛
D．解肌祛风，调和营卫
E．以上都不是
参考答案：D
—Was the driving pleasant when you went to Mexico last summer?
—No, it ________ (rain) for four days when we arrived, so the roads were very muddy.
函数y=xsin2x的导数是 [ ]
A.y′=sin2x-xcos2x
B.y′=sin2x-2xcos2x
C.y′=sin2x+xcos2x
D.y′=sin2x+2xcos2x
