美国和日本科学家近日通过分析采集来的三维地震数据，揭示了太平洋底南海海槽下的地壳结构。这一发现有助于科学家深入了解为什么地震在海底有些地方会引发大规模海啸，而在其他地方却不会。
这句话的主要意思是( )。

A．美国和日本科学家采集了三维地震数据
B．美国和日本科学家通过分析地震数据，揭示了太平洋底南海海啸槽下的地壳结构
C．美国和日本科学家研究发现了太平洋南海海槽下的地壳结构，使得科学家更清楚大规模海啸的规律
D．美国和日本科学家研究发现了太平洋南海海槽下的地壳结构，有助于科学家推测什么地方会引发大规模海啸

Personal firewall is a technology that helps (57) intruders from accessing data on your PC via the Internet or another network, by keeping (58) data from entering or exiting your system.
Hackers do not just target national security organizations for (59) : They want your tax returns, network passwords, or bank account numbers. And you do not want the FBI kicking in your door because someone hijacked your PC to (60) in the latest denial-of-service attack on the Internet. Now that "always-on" broadband connections such as cable modems and digital subscriber line are becoming more popular, home users are at risk. Fortunately, you can protect your data. Firewalls can block (61) attacks and protect your PC from outside threats.

A. allow B. prevent C. inviteD. get