问题
问答题 简答题
单模光纤与多模光纤在尺寸和使用场合上各有什么不同？
答案
参考答案：
单模光纤的纤芯直径为4μm～10μm，适用于高速长途通信系统。
多模光纤的纤芯直径为50μm，适用于低速短距离通信系统。
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单模光纤与多模光纤在尺寸和使用场合上各有什么不同？
参考答案：
单模光纤的纤芯直径为4μm～10μm，适用于高速长途通信系统。
多模光纤的纤芯直径为50μm，适用于低速短距离通信系统。
任务型阅读(共5小题；每小题1分，满分5分) 请认真阅读下面短文，在表格中填入适当的单词(注意：每空1个单词)。 How to protect children from unsafe material online has long been discussed in the USA. For some parents, the Internet seems like a jungle, filled with danger for their children. But jungles contain (包括) wonders as well as dangers. Most kids have started to use search engines. Many of them are great at finding lots of interesting websites, and they can also locate places where you might not want your kids to go. There are search engines designed just for kids. A certain software contains only sites that have been selected as safe. The most popular way to limit access would be to use what is known as a ‘content screener (过滤器)’. But this can’t be wholly reliable (可靠的), and the best thing parents can do is to talk to their kids and let them know what is OK or not OK to see or do on the Internet. Another way is that Mum or Dad is nearby when the child is surfing the Internet.
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