工程上所说的管道中流体的流速,是指断面()而言。
A.瞬时流速
B.最大流速
C.平均流速
D.最小流速
参考答案:C
The two newspapers gave different ______ of what happened.
A.versions
B.editions
C.productions
D.texts
汇票上不必记载“无条件支付的委托”的字样。