There is reason to believe that most writers have difficulty in ______ the opening paragraphs of their papers.

A．constituting

B．constructing

C．comprising

D．founding

在关节上腔造影许勒位闭口片上显示关节上腔呈“S”形，前部造影剂明显聚集，后部明显变薄，甚至完全消失。提示

A．可复型盘前移位

B．不可复型盘前移位

C．关节盘侧方移位

D．关节盘旋转移位

E．关节盘附着松弛