国家秘密的保密期限，除有特殊规定外，绝密级事项不超过20年，机密级事项不超过10年，秘密级事项不超过5年。

In order to reduce the accumulation of static electricity while loading petroleum products, you should（）.

A.start to load at maximum pressure

B.start to load slowly

C.increase the air flow into the tank

D.use the overall method of loading only