诊断肠旋转不良最可靠的方法是（）
A．腹部立位平片
B．B超
C．CT
D．钡餐造影
E．钡剂灌肠
参考答案：E
Having checked the doors were closed, and ________ all the lights were off, the
boy opened the door to his bedroom.
A．why
B．that
C．when
D．where
在规划干支渠时，为什么必须考虑灌区的排水问题？
