下图所示为按树状分类法对一组物质进行的分类。请填写下列标注。
混合物；单质
神经源性体位性低血压，卧位时血压__________，站立时血压下降__________。
I have great news for you. You have been accepted as member of our club.
A．a;a
B．a;the
C．the;the
D．/;a
