单项选择题
Vessels are required（）Singapore Port Service when passing the points indicated.
A.communicating with B.to communicate with C.be communicated D.will communicate
单项选择题 Vessels are warned（）in this area.
单项选择题 Vessels carrying（）must not willfully wash decks or holds.
单项选择题 Vessels must be（）valid certificate of nationality or certificated of registry or license.
