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  3. Since 1875, when Alexander Graham Bell first discovered how to send the human vo

Since 1875, when Alexander Graham Bell first discovered how to send the human vo

游客2024-01-11  31
问题 Since 1875, when Alexander Graham Bell first discovered how to send the human voice along wires, the telephone has been one of the world’s most utilized and essential methods of communication. The first telephone exchange in America was established in 1878 and served a total of 21 people. At that time, operators would answer a call and connect two parties by completing an electrical circuit. Little could those operators envision that, one century later, calls would be transmitted along optical fibers and, soon after, would become totally wireless and portable. The idea of orbiting satellites picking up millions of calls and relaying them across the planet would have been unimaginable. [br] Select the sentence that establishes the scope of the earliest telephone communications.
选项
答案 "The first telephone exchange... served a total of 21 people."
解析 The best answer is: The first telephone exchange in America was established in 1878 and served a total of 21 people. This sentence establishes scope by showing the limited circle of early users.
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