单项选择题 Mariners are FIRST warned of serious defects or important changes to aids to navigation by means of（）.

单项选择题 Lay days（）to commence after the expiry of a specified time after the giving of the notice of readiness to load or discharge.

单项选择题 In the absence of a custom or special contract to the contrary，the Shipowner is not bound to （）the consignees that he is ready to unload on arriving at the port of discharge.