In seventh grade ,he decided to go out for the cross-country team.为什么seventh前没有定冠词the?

In seventh grade ,he decided to go out for the cross-country team.为什么seventh前没有定冠词the?
In seventh grade ,he decided to go out for the cross-country team.
为什么seventh前没有定冠词the?

In seventh grade ,he decided to go out for the cross-country team.为什么seventh前没有定冠词the?
不是所有序数词前都加the；
用不用the,看是否特指.7年级,不是特指,你的7年级、别人的7七年级都一样,都是7年级,没必要说这个7年级、那个7年级.

seventh是序数词，不用定冠词