调节阀突然全开或全关是何原因？
参考答案：
1）检查气源和信号是否中断。
2）检查反馈杆是否脱落。
___ new products have been successfully made in the factory.
A．A great deal of
B．A number of
C．The number of
D．A great amount of
开证申请书内容应与合同内容一致。 ( )
