In a vacuum, the speed of a rocket isn't affected by atmospheric drag.

5. 在真空中，火箭的速度不受大气阻力的影响。

On earth, or Venus, or Titan, there's enough air that you can land largely unpowered, first by slowing down with a heat shield and atmospheric drag, and then with parachutes.

在地球、金星或泰坦上，有足够的空气可以让你在没有动力的情况下着陆，首先用防护罩和大气的阻力，再用降落伞减速。