Glider flight is a controlled descent; pilots gain altitude only if they catch rising air and ride it aloft.
用滑翔机飞行只是对下降的控制，真正的飞行员只有不断利用上升气流才能在空中越飞越高。
2
For example, you may not have experienced a ride in a rocket, but you could gain some understanding of this by listening to someone who explained his or her experience.
例如，你可能没坐过火箭，但当别人向你讲述了他的经历后，你就能对此有所了解。
3
But organising 5m drivers to fight back was a hard task, because each driver could hope for a free ride on the efforts of the others, and none had much to gain personally by joining the group.