我已经在初中三年了用英文怎么说

"I have been in junior high school for three years"

这是一句说明你已经在初中学习了三年的英语句子。

其中，"I have been" 是 "我已经"的意思，"in junior high school" 是 "在初中"的意思，"for three years" 是 "三年"的意思。

例句1：
I have been in junior high school for three years.
我已经在初中学习了三年。

例句2：
She has been in junior high school for three years.
她已经在初中学习了三年。

例句3：
He has been in junior high school for three years.
他已经在初中学习了三年。