I'm in tenth grade.这里tenth前面为什么没有加the cover,contain,include有什么区别

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 cover,contain,include有什么区别 （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. I live in New York.I am tenth grade in Senior High school.谁知道杂翻译? in tenth grade为什么序数词tenth前不加定冠词the I'm in Class 5 ,Grade 1 I'm in class 3,grade 5. I’m a student in Grade Seven. student I'm in Grade Two. I'm in Grade two,Class one I'm in Class one,Grade two I'm in Grade Nine.How can I go back to Grade Eight immediately? I'm in Class Nine,Grade Seven.什么样的提问才回答这句?.KKKKK I'm in Class One,Grade Seven.改为一般疑问句 I'm in the sixth grade.同义句 I'm in the sixth grade(用what提问） I'm in class one ,grade two改错 I'm in Grade 7.对7提问 ‘I’m in Class Two ,Grade Five.’的问句