BryanY988 Wrote:RonPurewal Wrote:ok, here's an example. i lived in miami about fifteen years ago.
consider:
I live in Miami.
RIGHT NOW this sentence is FALSE. (right now i live in los angeles.)
I have lived in Miami.
RIGHT NOW this sentence is TRUE (and it will remain true in perpetuity—it's clearly impossible for this to become false.)
The present perfect indicates either continued action or continued effect of a completed action up to the present.
As you live in LA now, the effect of action "live in Miami" is not up to the present. I cannot understand why use "have lived" here.
This is a very tough point, and as an instructor, I have yet to come up with a great, succinct way to explain it. Luckily, it doesn't matter very much. So don't worry if you feel like you don't understand why the second example is right, as long as you accept that it is, and don't accidentally count an answer choice as wrong because of it. (I know, I know, that's incredibly unsatisfying, especially if your ear isn't helping you out on this one!)
The additional rule of thumb, if you just want to memorize it, is that you can also use the present perfect to make general, true, currently relevant statements about what someone/something has done in the past. For instance, if I say 'I have already eaten breakfast', I'm not really talking about my breakfast specifically, just saying that I ate breakfast at some point this morning, and now I'm not hungry. That's what really matters - that I'm not emphasizing the specific time when I ate breakfast, just trying to say that right now, I'm not hungry anymore. Note that it'd be very weird to say that sentence if I'd last eaten breakfast three days ago, because it'd no longer have current relevance. In that case, I'd say 'I ate breakfast on Thursday' instead.
Something else you can do, is compare the present perfect to the past tense. Some students don't have a 'feeling' for this, but some do, and you very well might. Think about the difference between these two sentences:
I saw Titanic fifteen times.
I have seen Titanic fifteen times.
You'd probably use both of these interchangeably, if you were just talking. And you'd never, ever have to choose one over the other on the GMAT. But they might 'feel' subtly different to you. There is a lot of overlap, and both are grammatically right - for example, Ron could say either 'I have lived in Miami' or 'I lived in Miami', and either one would be true. It's just a question of what the sentence is emphasizing, which isn't something the GMAT cares about. Lucky! You're not going to see sentences on the GMAT where you have to make subtle decisions about meaning like this. If there's a meaning issue that you should use to decide on the answer, it'll be real stinking obvious. What you should really care about is whether the sentence is breaking any of the grammar rules of present perfect, like 'don't switch tenses mid-sentence unless there's a clear reason to'.