I'm in the tenth grade 和I'm in tenth grade.都对吗,有什么不同啊,谢谢

I'm in the tenth grade 和I'm in tenth grade.都对吗,有什么不同啊,谢谢 I'm in tenth grade.这里tenth前面为什么没有加the in tenth grade （高一）十年级：I'm in tenth grade,前面为什么不加the 请详细说明理由. 英语翻译In the tenth grade,I began volunteering at a veterinary I live in New York.I am tenth grade in Senior High school.谁知 I'm in Grade two,Class one I'm in Class 5 ,Grade 1 I'm in class 3,grade 5. I‘m in class Four grade I’m a student in Grade Seven. student I'm in Grade Two.