单项选择题
A.validity in
B.valid for
C.effective at
D.effectiveness for
单项选择题 （）of this Deratting Exemption Certificate is hereby extended until 4th Oct.2007 as the vessel is laden with cargo.
单项选择题 If there are any Certificates expired or nearing expiry the master of a ship must shall apply fortheir （） at any port.
单项选择题 My Deratization Exemption Certificate will become （）on the 16th of September.