套管冷凝器的内管走空气，管间走饱和水蒸气，如果蒸气压力一定，空气进口温度一定，当空气流量增加时，总传热系数K应增大，空气出口温度会提高。
参考答案：错
Though _______ money, his parents managed to send him abroad. [ ]
A. lacked
B. lacking of
C. lacking
D. lacked in
54+（54×3-54）÷2中，最后一步求（ ）
A．和
B．积
C．差
D．商
