你要看什么时态？
如果是现在还在上，就写成现在进行时。
I am studying in Neijiang Number 8 Elementary School.
我正在内江八小学习。
I have been studying in Neijiang Number 8 Elementary School for ... years.
我已经在内江八小学习了。。。年了。（强调学习中）
I have studied in Neijiang Number 8 Elementary School for ... years.
我已经在内江八小学习了。。。年了。（强调几年中）
如果你已经毕业了，就写成过去时态，根据语境不同，可以有过去完成式，过去进行时，和一般过去时。
I had studied in Neijiang Number 8 Elementary School when I was ... years old.
在我。。。岁的时候，我已经完成内江八小的学业了。
I was studying in Neijiang Number 8 Elementary School.
我那时候，在内江八小学习。
I studied in Neijiang Number 8 Elementary School.
我在内江八小学习过。