单项选择题 Which current is responsible for the movement of icebergs into the North Atlantic shipping lanes（）.

单项选择题 When there are small differences between the heights of two successive high tides or two successive low tides，the tides are called（）.

单项选择题 When daylight savings time is kept，the time of tide and current calculations must be adjusted.One way of doing this is to（）.