in my life i have many mistakes so i don't know which one is unforgettable mistake. But i think many of my mistakes come from myself,especially my decision isn't decisive enough that make me miss many things. my biggest mistakes in decision making is about to being a rotary exchange student in 2016-17 because i would have been a rotary exchange student since last years if i have had bravery to face with various obstacles in exchange student life. From all of these i think i should brave to make decisively decision.