问题
单项选择题
在AIS系统中，VHF收发机在发射信号时，（）发射信息。
A．使用87B国际专用频道
B．使用88B国际专用频道
C．交替使用87B、88B两个VHF国际专用频道交替
D．同时使用87B、88B两个VHF国际专用频道
答案
参考答案：C
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在AIS系统中，VHF收发机在发射信号时，（）发射信息。
A．使用87B国际专用频道
B．使用88B国际专用频道
C．交替使用87B、88B两个VHF国际专用频道交替
D．同时使用87B、88B两个VHF国际专用频道
参考答案：C
Nowadays, we have tons of high-tech gadgets to help us keep connected to our friends and family. Many of us have cellphones to ___16__ calls and write text messages; the Internet to chat with friends and __17__ e-mails. But being in touch with your friends and family also means __18__ in touch with some strangers. We often get spam(网上垃圾邮件) in our inbox, calls from strangers, and messages from __19__ people. So what should we __20__ with all of these? __21__ you might want to answer the call from an unknown number, or respond to the message from someone you don’t know, try __22__. You are not sure __23__ they are contacting you, and it could be ill-spirited. It is __24__ not to respond to calls or messages from numbers that you are not familiar __25__. The same rule applies to (应用于) e-mails. There are many people who create viruses that __26__ harm your computer, and these viruses are disguised(假装) as e-mails. __27__ opening these e-mails, you are risking getting a virus __28__ could destroy your computer. In other words, all the new technology is great for keeping in touch, but also comes with some bad things. __29__ yourself out of trouble, it is best to __30__ from messages and calls that you don’t know.
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