The sailors should show relevant flags by day or pilot lamps at night.
问题描述：
The sailors should show relevant flags by day or pilot lamps at night.
答
船员应该在白天展示有关的旗帜，到了晚上舵手要亮灯。
答
水手应该在白天挥动相关的旗帜或者在晚上打出指示灯