鉴别柯兴病和肾上腺腺瘤选用
A．体位试验B．CRH兴奋试验C．小剂量地塞米松抑制试验D．大剂量地塞米松抑制试验
参考答案：D
They've kept up a friendship with the teacher whom they were at school _____ twenty years ago.
A．with
B．about
C．since
D．till
流通国债是指可以在流通市场上交易的国债。这种国债的特征是投资者可以自由认购、自由转让，通常不记名，转让价格取决于对该国债的供给与需求。( )
