A. 普通包裹 B. 快递包裹 C. 韵达快递 D. 挂号信
A. 立即变为0 B. 恒定 C. 下降 D. 增加
A. saltwater heater shell B. the condensation of the saltwater feed C. air ejectors, eductors, or a separate vacuum pump D. condensation of the distillate