Travel to the moon was inconceivable until recently.

不久以前,登月旅行还是不可思议的事情.

Would you travel to the moon commercially if given the chance?

若有机会，你是否到月球做一次商业旅行？

It once seemed inconceivable to everyone that men should travel to the moon.

认为，人飞上月球似乎是不可想象的。