77.It is a waste of time playing comuter games. it's a waste of time doing sth做某事浪費時間
78.To my surprise, he changed a lot last year.
79.He used to be the tallest student in the class. used to be曾經,過去....
80.In order to get up on time, she set her alarm clock. set the alarm clock 設定鬧鐘