题目

Sorry, we are late,--our plane was _____ because of the heavy rain. A. held out           B. held on         C. held up            D. held back 答案：C 解析: 略食品放入电冰箱后，温度降低，其内能的变化及其变化方式是A.减小、热传递B.减小、做功C.增大、热传递D.增大、做功