2017年理工類職稱英語考試詞匯選項(xiàng)押題

Radar is now a familiar tool. Like many others it was an unexpected discovery. It was first observed by two researchers, who were studying sound communication. They were sending signals from a station on one side of a river in Washington D to a vehicle across the river. They discovered that their signals were stopped by passing ships. They recognized the importance of this discovery at once.
    The main idea of this paragraph is__________.
    A、Study of Radar
    B、Radar is now a familiar tool
    C、Radar Working Principles
    D、Radar was Discovered by Chance
    【正確答案】D
    【答案解析】unexpected，“沒有預(yù)見到的”，等于答案D中的by chance“偶然間的”。