The advantage of the balloon is that it will be cheaper than a space plane or rocket.
气球的优点是它比航天飞机或火箭便宜。
2
It was to take off and land like a plane, but soar into outer space like a rocket.
它像一架飞机一样起飞和着陆，也可以向火箭一样飞进外层空间。
3
Rocket Men: Saturn V, which carried the Apollo 11 Moon mission, climbs toward orbit after lift-off in a photograph taken from a plane monitoring the launch.