[討論]GWD1-Q7

[ad264]

請教一下on average & an average of用法，在什麼時候是不正確？

這一題CEO莫伯伯說過沒有人賺平均數，但是PP有一題卻是人可以省平均多少錢。

Compared with nonrunners, people who run three days a week save an average of 14.1 percent on health-care costs each year in the United States.

謝謝