VOA慢速英语:Remembering the X-15, America's First Step in Manned Space Flight

push against(使)推, 顶〔按〕…

例句：Don't push against the fence.
      别推篱笆。

      Push against temptation and you will get muscle in your character.
      如果你能抵制诱惑, 你的性格就会坚强起来。

2.Nor could it take off from the ground. It was carried into the air by a B-52 bomber.

take off(飞机)起飞

例句：It's exciting to feel the plane taking off.
      感觉到飞机起飞令人兴奋。

3. Much of what was learned from its flights speeded up the development of the space program.

speed up(使)加速

例句：We'll never get there if he doesn't speed up.
      如果他不快些走, 我们一定到不了那里。

      We are speeding up the mechanization of our agriculture.
      我们正在加快农业机械化的步伐。