“我学了2年英语”怎么说？

我断断续续学习了12年英语了。
I've been learning English off and on for 12 years.
到去年年底我们已经学了6年英语。
By the end of last year we had studied English for five years.
我们大部分人已经学了5年英语了。
Most of us have studied English for 5 years.

I have learnt English for 2 years.

I have learned English for two years.

错啦~~
study是非延续性动词，而且for不能喝ago连用
您的句子杂糅了~~
你可以说 I studied English two years ago
也可以说I have been studying English for two years.