Grades six还是grade six?grade作等级讲用复数吗?我的课本上写着grades six to grades twelve
问题描述：
Grades six还是grade six?grade作等级讲用复数吗?我的课本上写着grades six to grades twelve
答
应该是单数啊!Secondary school in the US usually covers seven years ,grades six to twelve是课本原句