一座山峰被冲刷进海里前能存在多少载？
How many years can a mountain exist before it 's washed to the sea?
在进入封闭空间前，(如压载水舱)应作什么准备工作？
Before entering an enclosed space such as ballast tank, what action will you take?
在进入封闭空间前，(如压载水舱)应作什么准备工作？
Before entering an enclosed space such as ballast tank, what action will you take?
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