词根词缀：grad-, -grade, -gred, -gree, -gress

【来源及含义】Latin: walk, step, take steps, move around; walking or stepping

【同源单词】ad eundem gradum, aggradation, aggression, aggressive, aggressively, aggressiveness

词根词缀：retro-, retr-

【来源及含义】Latin: back, backward, backwards; behind

【同源单词】arrear, regurgitant menstruation, retroact, retroaction, retroactive, retroactively