According to conflict theorists, social control agents and systems are ______.

A．liberal

B．partial

C．neutral

D．overall

下列哪项不属于切口感染的预防措施

A．术中严格无菌操作

B．避免异物存留

C．避免切口内血肿

D．及时有效的局部理疗

E．术前纠正患者贫血、低蛋白血症