Andrew Johnson, who served out Lincoln's second term after the assassination, and Bill Clinton. Nope, can't count Richard Nixon on a technicality. He resigned before the House could vote up the articles of impeachment. ... No president has ever been impeached, convicted and removed.
The country that refused was France
A. Existence of social classes...Under capitalism those who collect another's funds in a voluntary transaction become rich (if they also run their business with a high enough profit margin) whereas under socialism: A "family" (like LBJ's and their Democrat FCC broadcast monopoly "licenses") is "granted" special privileges by the "rulers" and end up from nothing to the 100's of millions
The application of scientific knowledge for practical purposes, especially in industry.