单项选择题
A．have to travel a greater distance B．move less quickly C．travel much quickly D．be less powerfull
A．we will notice that it is not moving B．we cannot tell whether or not it still exists C．it will be brighter than the moon D．it is four years that the light we can see will reach us
A．a student B．CEO of a company C．doing business in Shanghai D．both A and B