Our maths teacher set so difficult an examination problem ______ none of us worked out.

A．which

B．that

C．as

D．so that

患者，男，39岁，发现两下肢水肿半月，呈凹陷性，直至膝下，血压正常，小便频数，大便软，纳可，舌边稍红，苔薄白，脉细滑。

治疗应首选（）

A.苓桂术甘汤

B.真武汤

C.实脾散

D.防己黄芪汤

E.萆薢分清散