英语语法分析

In experimenting we find out that sound travels with different velocities through different substances.

在实验中，我们发现声音以不同的速度通过不同的物质而传播。

《新英汉大辞典》

By compiling a map of seismic velocities from thousands of earthquakes across the globe, they can also begin to map temperatures and densities throughout the mantle.

通过编制全球数千次地震的地震速度图，他们还可以开始绘制地幔的温度和密度图。

We will discuss velocities and acceleration.

这节课主要讨论速度和加速度。