in a middle school 還是 in middle school
要看你在語句中的應(yīng)用情況,若你要介紹自己曾經(jīng)在某一所學(xué)校就學(xué),又系句中首次提及,加不定冠詞"a",若僅僅是泛指在中學(xué),可以不加不定冠詞"a".
例如：When I was twenlve years old I went to a middle school,in which I finished my school education.；In middle school,the students in China have to learn more scientific subjects,such as physics,chemistry,maths,and so on.第二句的"middle school"后面可以加"s",表示復(fù)數(shù).
上述解答是否適合你問題的原意,