2. Key word
1.Fiber-optic
Reason:Because it is used many times.
2.Telephone system
Reason:Because it is painted blue color.
3.Cable TV system
Reason:Because it is painted blue color.
4. Sentence
1.Fiber-optic lines are stands of optically pure
glass as thin as a human hair that carry digital
information over long distances.
Reason:Because if this sentence is not exist,
the section is not concluded.
5. Sentence
2.They are also used in medical imaging and
mechanical engineering inspection.
Reason:Because if this sentence is not exist,
the section is not concluded.
6. Sentence
3.You hear about fiber-optic cables whenever
people talk about the telephone system, the
cable TV system or the Internet.
Reason:Because if this sentence is not exist,
the section is not concluded.
