单项选择题
After an IOPP Certificate is issued to an inspected vessel，how many other surveys of the vessel’s pollution prevention equipment are conducted during the period of validity of the certificate?（）
A.None B.One C.Two D.Three
单项选择题 ACCIDENTAL ESCAPE OF OIL OUT OF A TANK WHEN IT GETS TOO FULL BECAUSE PUMPING WAS NOT STOPPED IN TIME defines（）.
单项选择题 A wooden plug fitted tightly in the vent of a damaged tank may prevent the tank from（）.
单项选择题 A virtual rise in the center of gravity of a ship may be caused by（）.
