题目

It is said that potato chips ______by mistake about a hundred years ago. A. invent                                                                  B. invented C. are invented                                                          D. were invented 答案：D  句意：据说薯片是大约一百年前偶然被发明的。本题考查动词的时态和语态。由时间状语a hundred years ago可看出句子应用一般过去时；potato chips与invent构成被动关系，故选D项。

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