填空题 This new method not only saves time but also saves energy 1 operating on two batteries inside of four.
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【正确答案】 1、by    
【答案解析】解析： This new method (方法)not only saves time but also saves energy(能量) by operating(运行/工作) on two batteries电池 instead of four. 这种新方法不仅节省时间，而且还节省了两个而不是四个电池经营能源