患者，男，16岁，2天前有进不洁水果史，现出现发热38．4℃，腹痛、腹泻，里急后重，大便次数逾10次／天，已用过氯霉素、卡那霉素未见效果，仍有脓血便。选用下列何种药物较有针对性（）

A.氟喹诺酮类药物

B.庆大霉素

C.四环素

D.加大卡那霉素剂量

E.红霉素

Virtualization is an approach to IT that pools and shares (86) so that utilization is optimized and supplies automatically meet demand. Traditional IT environments are often silos, where both technology and human (87) . are aligned around an application or business function. With a virtualized (88) , people, processes, and technology are focused on meeting service levels, (89) is allocated dynamically, resources are optimized, and the entire infrastructure is simplified and flexible. We offer a broad spectrum of virtualization (90) that allows customers to choose the most appropriate path and optimization focus for their IT infrastructure resources.

A．profits

B．costs

C．resources

D．powers