I don't think Richard could have done such a stupid thing last night, _____?       [ ]

A. do I            

B. could he      

C. did he      

D. has he

消化道穿孔的临床特点有

A．突然剧烈腹痛，呕吐

B．必有胃十二指肠溃疡病史

C．板样腹，压痛、反跳痛、肌紧张

D．肠鸣音减弱或消失