A. an electric instrument of sight. B. a simple adding machine. C. a way to keep employees honest. D. an expensive piece of window dressin 参考答案:A 答案解析:细节题,只是选项的表述与原文相比有所变动。关键词为“nothing more than an electric eye”,“nothing more than”意为“只不过,不外乎”。电子眼的具体功能