Is this sentence correct?

big dream Hi,Is this sentence correct?As we entered the new mellennium, it have become one of the things that everybody is talking about, both within and outside of the academia.Thanks.

No. The subject-verb is not in agreement; the tenses need to be consistent; there is a spelling mistake, and there should be no article before academia.

As we entered

Thanks a lot.

But, I think the meaning has changed.

As we entered the new millennium, it had become one of the things that everybody was talking about, both within and outside of academia.

In the new sentence, no one in the present time speaks about "it." I want to say that "it" is still one of the things that everybody is talking about.

C

You set the time frame of the sentence in the first clause:

As we entered the new millennium

This is past tense, 12-13 years ago, and the conjunction "as" means that the rest of the sentence is happening at that same time.

So if you want the present time, you have to change the initial clause.

Is the following correct?

Since we entered the millennium, it has become one of the things that everybody is talking about, both within and outside of academia.

Thanks.

Yes. That's fine.