This dictionary is at least three times as thick as        you borrowed from the library

A．one

B．that

C．it

D．those

发生切口疝最主要的病因是（）

A.腹部手术切口为纵形切口

B.切口过长，缝合不够严密

C.引流物放置过久

D.切口发生感染

E.病人术后腹胀