Backcrawl
= backstroke
🗣️ 情景例句
A serious matter.
一个严重的问题。
Poverty is not a crime.
贫非罪。
If we could actually see the path described by a particle,such as a sand grain in the rock,
假如我们真能看到的运动轨迹，诸如岩石中一个沙粒分子