When an object is seen moving in relation to a stationary object, the stationary object is called the frame of reference or reference point.

they spoke with the president

explanation:

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".