serial and rotation numbers

• 次数

serial and rotation numbers的用法和样例：

例句

1. He played the piano less and less as he grew older.
   他随著年龄的增长，弹钢琴的次数越来越少了。
2. We track all referrals and rank them accordingly.
   我们将根据您推荐朋友的次数排列位次。