medium 指按照某种标准来说是适中或中等的。这种标准可以是通过仪器测量而来，也可能是凭经验而得出。
average 通常用来形容优劣难分的平庸或折衷情况，也指理论上的平均标准。
参考例句
1. The children average seven years of age. 这些孩子平均年龄为7岁。
2. On average, I spend 100 on books each month. 我平均每个月花在买书的钱有100 元。
3. How much do profits, on the average, amount to? 那么，平均而言，利润的总量又有多少呢？
英英解释
n.
1. a statistic describing the location of a distribution
2. amount to or come to an average, without loss or gain
3. achieve or reach on average
4. compute the average of adj.
1. approximating the statistical norm or average or expected value
2. lacking special distinction, rank, or status; commonly encountered
3. lacking exceptional quality or ability
4. around the middle of a scale of evaluation of physical measures
5. relating to or constituting the most frequent value in a distribution
6. relating to or constituting the middle value of an ordered set of values (or the average of the midd
