劍橋詞典(of an error ) caused by a mistake a player has made rather than as the result of their opponent's skilful play 主動的（失誤） done as a result of your own decision , rather than being forced by someone else 非強迫的，自願的 an unforced agreement between individuals about what to do 個人之間對如何行動的自主協(xié)議 happening or done without any effort 不費勁的，不勉強的，自然的 natural , unforced laughter 自然且自發(fā)的笑聲 返回 unforced