英语翻译when night falls,colours become fainter to the eyes and

英语翻译
when night falls,colours become fainter to the eyes and finally disappear.after your eyes have grown used to the dark,you can see better if you use the sides of your eyes rather than the centers.sometimes,after dark,you can see a small thing to one side of you,which seems to disapear if you turn your head in its direction.this is because when you turn you head,you are looking at the thing too directly.men on guard duty sometimes think they see something moving to one side of them.when they turn to look straight at it,they can't see it any more,and they believe they were mistaken.however,this mistake happens because the center of the eyes,which is very sensitive in daylight,is not as sensitive as the sides of the eye after dark