Trails
n. 山径；游径；踪迹（trail的复数）
🗣️ 情景例句
It's next week from this Monday.
下个星期一。
What kind of climate do you have?Is it humid?
你们那里的天气怎么样？它是潮湿的吗？
and by measuring the time interval between the taps and the receipt of the echoes, the depth of the sea at that point can be calculated.
测出回声间隔的时间，便可算出该处海洋的深度。