可有可无
量力尔行
因祸得福
适可而止
喋喋不休
參考答案:可有可无:unnecessary
量力尔行:a man can do no more than he can
因祸得福:a blessing in disguise
适可而止:know when or where to stop
喋喋不休:(1)blat cackle chackle harp harp on jaw-jaw rattle twitter wag
喋喋不休:(2)ciarlare babble (这个我不确定，托福考试词汇里这么说的)
