第27题: [单项选择]Microwaves are ______. A. absolutely safe at low levels B. very efficient for cooking C. cancer-causing iii people with weak eyes D. completely understood by scientists 参考答案:B 答案解析:根据文章第三段对微波特性的叙述,作者得出"cooking process is much more efficient than in conventional ovens”,故选项B正确。从最后一段