【单选题】Man: Can't we slow down? Don't you feel tired? Woman: Slow down? Don't you realize that it is already half past eight? Question: What does the woman's response mean?
【简答题】在外径为 140mm 的蒸气管道外包扎保温材料,以减少热损失。蒸气管外壁温度为 390 °C ,保温层外表面温度不大于 40 °C 。保温材料的 λ 与 t 的关系为 λ =0.1+0.0002 t ( t 的单位为°C, λ 的单位为 W/ ( m· °C ))。若要求每米管长的热损失 Q/L 不大于 450W/m ,试求保温层的厚度以及保温层中温度分布。