DynaTAC 8000X was a______(2 words)often called "the brick."

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问题 DynaTAC 8000X was a______(2 words)often called "the brick."
  
Until nineteen seventy-three, most telephone calls were made either at home, at a business or in a vehicle. But on April third of that year, Martin Cooper of the Motorola Company made history. While walking down the street in New York City, he made the first mobile telephone call.
    Mr. Cooper had helped invent the DynaTAC 8000X. It was a mobile telephone often called "the brick." It was much larger and heavier than the mobile phones we use today. After that first call, it took ten years before the phone was ready to be sold to the public. The first ones were very expensive. They cost almost four thousand dollars each. But even with that size and cost, many people stood in line to buy them.
    The first mobile telephones used a system, or network, called 1G. It was the "first generation" of technology. This allowed one person to call and talk to another person, but that was all. By the early nineteen nineties, the second generation, or 2G network, came into use. It allowed talking and sending text messages. By that time, cell phones were much smaller and cost much less.
    In two thousand and one, the first 3G systems were being used. This new network permitted people using cell phones to make calls, send text messages and use the Internet. Users could even keep photographs and music on their phones, and send them to their friends.
    Within the past two years, the 4G network has come into use. It permits cell phones to work much faster and with much more information. Modern cell phones can even act as small televisions. They can show movies and live sporting events.
    As the networks have gotten more complex, the telephones have gotten smaller, lighter and less costly. Many electronics stores in the United States even give away the newest cell phones. But customers must agree to pay to use the network that sends their calls from one place to another. It is interesting to imagine what the 5G and 6G network cell phones of the future will be able to do.

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答案sending text messages

解析 sending text messages文中说:20世纪90年代初,第二代或2G网络开始使用。它可用来交谈和发送文本短信。到那个时候,手机较以前小得多,且成本低得多。
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