Echoranging
回声测距法
🗣️ 情景例句
I see how people spend their leisure time--
我看到人们怎样利用闲暇时间
I underestimated the cost of the journey.
我对旅行费用估计不足。
First of all, they may have come to this planet of ours thousands or millions of years ago,
首先，他们可能在几千年前或几百年万年前已来过我们地球，