on the average / on average / on an average三者区别是什么

Question

这三个词组是否都对,有什么区别呢

Answer 1

on the average
on the average[简明英汉词典]
平均,按平均数计算;一般地说

on average
on average[简明英汉词典]
平均起来

on an average
on an average[简明英汉词典]
adv. 作为平均数