How can someone's clothing show that they have fired a gun?

We can tell someone’s clothing show that they have fired a gun when the burning gunpowder residue stays or remains on the clothes. If the clothes test positive for GSR gunshot residue it means that it is very close to a gun that was fired. Remember that a traces of a gunpowder residue remains on clothing or skin and on the surface after discharging a firearm is 78 hours.  

the first forms of writing came from them in the form of pictographs around 3100 bc.

its main object was the establishment of "settlement houses" in poor urban areas, in which volunteer middle-class "settlement workers" would live, hoping to share knowledge and culture with, and alleviate the poverty of, their low-income neighbors.