应该是on a school day还是at a school day

应该是on a school day还是at a school day 写A day at school well,have a good day at school. A day at school 英语作文 We have ( ) school Day at our school.( )中应填a还是an还是不填 have a school day A day in school a school day作文 We have a school day at our school Do you have a School Day at your school? do you have a school day at year school是什么意思 英语翻译Mr Day was a teacher at a school in a big city on the no