装有偏心井口装置的抽油机井口设备与一般抽油机井口设备的不同部件是（）。
A、生产阀门
B、偏心四通和法兰
C、防喷盒
D、四通大法兰
参考答案：B
In the context of corporate governance explain the role of the external company auditors, paying particular regard to the following issues:(a) their qualifications;(b) their powers;(c) their duties. (10 marks)
炉热的铁水温度高，铁沟的火花（）。
A.细密而红
B.跳得矮而暗
C.跳得高而亮
