The manager was worried about the press conference his assistant _____in his place but ,luckily ,everything was going on smoothly.

A．gave

B．gives

C．was giving

D．had given

人工关节置换术后最常见并发症是（）

A.泌尿性感染

B.骨折

C.膀胱损伤

D.急性肾功能衰竭

E.胃肠道出血