2003年之前，国际石油价格一直在每桶30美元以下。到2004年超过每桶55美元。2008年1月2日，新年第一个交易日，竞超过每桶100美元大关。国际市场石油价格上涨的最主要的原因是（）。

A.生产石油的劳动生产率降低了

B.国际贸易中未能贯彻等价交换原则

C.生产石油的个别劳动时间增加

D.石油生产增长跟不上预期消费增长

To compete in today’s fast-paced competitive environment, organizations are increasingly allowing contractors, partners, visitors and guests to access their internal enterprise networks. These users may connect to the network through wired ports in conference rooms or offices, or via wireless access points. In allowing this open access for third parties, LANs become (171) . Third parties can introduce risk in a variety of ways from connecting with an infected laptop to unauthorized access of network resources to (172) activity. For many organizations, however, the operational complexity and costs to ensure safe third party network access have been prohibitive. Fifty-two percent of surveyed CISOs state that they currently use a moat and castle’s security approach, and admit that defenses inside the perimeter are weak. Threats from internal users are also increasingly a cause for security concerns. Employees with malicious intent can launch (173) of service attacks or steal (174) information by snooping the network. As they access the corporate network, mobile and remote users inadvertently can infect the network with (175) and worms acquired from unprotected public networks. Hackers masquerading as internal users can take advantage of weak internal security to gain access to confidential information.

（175）是（）

A.sickness

B.disease

C.viruses

D.germs