第7题:[单选题] 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 参考答案:D 【参考译文】IOPP证书已签发给受检船。在证书有效期内对防污设备的检查须进行几次?三次。 【解 析】pollution prevention equipment防污设备