I hate travelling by air__________ you usually have to wait for hours before the plane takes off.

A．because

B．though

C．until

D．unless

在用厂内机动车辆的规章制度包括岗位责任制、（）和岗位操作规程。

A.产品质量检验

B.安全管理制度

C.考勤制度

D.产品抽查