單項選擇題

The shipboard oil pollution emergency plan will be invalid after （）

A.one year
B.two years
C.four years
D.five years

你可能感興趣的試題

單項選擇題

（）connectors hold best if a wire is accidentally pulled or a connection becomes loose.

A.Ring type
B.Fork type
C.Spade type
D.Push on pull off type

單項選擇題

（）are used to digest the sewage to produce innocuous sludge in a biological sewage treatment plant.

A.anaerobic bacteria
B.aerobic bacteria
C.air bubbles
D.disinfection chemicals