化脓性梗阻性胆管炎常见的病因是（）。
A.括约肌痉挛
B.胆管结石
C.T管造影术后
D.胆管狭窄
E.胆管蛔虫
参考答案：B, D, E
伸缩缝的伸缩量如何计算？
They were all so tired that they could ______.
A．do nothing but sleep
B．do anything but sleep
C．do nothing but to sleep
D．do anything but to sleep
