[单选] 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?（）

All the cargo holds must be（）cleaned out（）meet the requirement of the cargo surveyor. such／that。 so／that。 such／to。 so／as to。 简述CN1～CN7的功能与连接。 在服务器可以确认用户身份之前，必须建立有效的（）的帐户。 Windows 2000。 98。 Windows。 服务器。 200km/h既有线地面应答器的配置原则是什么？ 煤热解形成半焦后继续加热，在700℃附近，一面发生收缩，一面产生以（）为主的煤气。 H₂。 CO。 CH₄。 C₆H₆。 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?（）