汽轮机冷态启动的初始阶段，蒸汽对汽缸内壁的放热属于（）放热。
A、膜状凝结
B、珠状凝结
C、对流
参考答案：A
This book sells well, more than 1,000 copies_____ yesterday. [ ]
A. sold
B. are sold
C. were sold
不能用来登记现金日记账的记账凭证是( )
A．现收凭证
B．现付凭证
C．银收凭证
D．银付凭证
