圆柱形容器的受力不均匀，根据受力分析，环向焊缝所受的应力要比纵向所受的力（）。
参考答案：小
急性化脓性梗阻性胆管炎的治疗应选用（）
A.急诊胆囊切除术
B.胆囊造口术
C.非手术疗法控制感染
D.切开减压引流胆总管
E.切开减压引流胆总管并胆囊切除术
— Where are the twins?
— I think they _____ Hangzhou. They _____ there twice before. [ ]
A. have been to; has gone to
B. have gone to; have been
C. have been to; have been to
D. have gone to; have gone
