One of his first experiments after the telephone bettered the phonograph.他在发明电话后首次的一项实验中,改善了留声机的品质.He bettered his last year's record.他刷新了他去年的记录.As an account of adolescence it could hardly be bettered.作为描写青春期的书，它已几...

betterment的复数形式为：betterments...