对流板可提高罩式退火炉的传热效率。（）
参考答案：对
为使管路系统按所需的流量Q正常运行，所选择的输送机械必须条件？
— Did you talk with _______ present at the meeting yesterday?
— No. Only a few of them. [ ]
A. anyone
B. everyone
C. someone
D. no one
