题目

人工降雨时，飞机向云层中喷撒干冰（固态二氧化碳），干冰吸热，云层中水蒸气凝华成小冰晶，冰晶变大后，下落时成水，落到地面形成了雨。（均填物态变化名称） 答案：【1】升华【2】熔化---The boss said we had only three days to finish the work.---Don't worry. We have already __________two thirds of it.A. got down B. got throughC. given in D. given away