I am at school与I was at school的区别

I am at school与I was at school的区别 I am at school 还是 I am at a school I was popular at school I am a 什么 at willow school. I am always b__ at school. I am in No.5 Middle School与I am at No.5 Middle School这两种表达都正确吗? I think I am popular at school.(改为一般过去时) I am in school和I am at school有什么不同 i am in school i am a school WHEN I WAS AT HIGH SCHOOL OR WHEN I WAS IN HIGH SCHOOL? i am in year 7 at walker school是什么意思? I am in Year 8 at Woodland School I am at school today.( 用yesterday代替today) 改错At presently I am a senior high school student I am at a new school now(同义句转换) am,a,i,good,student,school,at连词组句 用So.或Neither.倒装以下句子I have got a bad cold.I have not got a pen.I was at home.I was not at school.I am not Korean.I went to town.I did not stay at home.I can swim.I can not ride a horse.I live in China.I do not like fish.再详细说明