that, which，what; efficient, efficiently, efficiency A green product is one_________has less impact on the environment, using less resources, creating less waste, and being more energy _________.
【正确答案】：that; efficient
【题目解析】：此句的意思是一个环保产品是对环境影响较小，占有较少资源，产生较少废物，能源更加高效。先行词有one后面的分句用that来引导。Being后面需要用形容词和more一起构成形容词的比较级，efficiently是副词，efficiency是名词。