The usage for the word "long"

English as a Second Language English Vocabulary, Grammar and Idioms
1

First, thanks for viewing this post.

Here is my question: in the sentence “I have long acknowledged this problem…”, is the word “long” grammatically correct using in this way?

2

Hello.

That sentence is correct. It is the equivalent to ‘I have acknowledged this problem for a long time.’

3

Thank you very much.