How do you know when a mail truck has moved

If you mean, how do you know where the mail truck has moved to different address. A customer has deposited a letter destined for a distant address in a collection box, a postal carrier removes all of the mail from the box and takes it to the Post Office where he or she works. That letter and mail collected by other carriers of that Post Office are placed on a truck and taken to a mail processing plant. 

Otherwise, I need more info to help you with the question. But I hope this helps.

as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

not copied too! hope this !

joke:

h o h o hope you have a merry christmas!