形成油气藏必须具备生油层、储油层、盖层（）等条件

A.气顶

B.边水

C.油气运移

D.底水

A CO₂ extinguisher on a ship which has lost 10% of its charge must be（）.

A.used at the earliest opportunity

B.hydro-tested

C.recharged

D.weighed again in one month