The simple past and past perfect tenses confuse a lot of people, so here’s a little help. But first a little expostulation. Languages vary in how they do verb tenses. In German, they use the present perfect for the past, most of the time. In Hebrew, they don’t even have a present tense for the verb “to be.” If the verb is missing, you assume it’s a present tense of to be. In fact, the name for God, as far as we can tell is what would be the first person masculine present tense of to be, “I am.” We don’t know for sure how to pronounce it because that verb in Hebrew (and all other languages I’ve seen) is highly irregular, and besides, classical Hebrew was (still is) written without the vowels. And yes, Hebrew verbs show gender. A guy doing something is a different word than a gal doing it. (I know, you want an example. A guy saying “I love” would say something that sounds like “Anee ohayv” and a lady saying the same thing would say “anee ohevet.”)
Enough of the technical stuff about non-English.
Use the past when something happened in the past, period, especially if you mention the time. Use the present perfect if the thing happened in the past and continued until now. Use the present perfect progressive if something started in the past and isn’t finished yet. And use the past perfect if something happened in the past, continued for a while, then ended in the past.
Here’s an example of how not to do it, from NASA (or one of their fans) no less. I apologize for not having a screen shot–I collected this error before the post about having more pictures. I’ll make it up to you later.
NASA has created an “Astrobiology Roadmap” in 2008 that outlines pathways for research and exploration…
This describes the creation of the roadmap as a single event, so they should have said, “NASA created etc.” The present tense for “outlines” is okay, because the map still outlines the pathways, even though they created the map a while back. (Yes, some would argue that the effect of the creation continues to the present, and I would grudgingly grant them their point.) The issue is clearer if the writer had said something like “Last year NASA created…” Clearly past tense, on that one, eh?
Here’s a rule of thumb: Try using the simple past tense. if it works, use it. Don’t bother with the present perfect.
Here’s a good use of the present perfect: You’re a kid, and Auntie Mabel comes over for a visit, and she gushes
My how you’ve grown!
Growing is something that takes place over time, so the present perfect is appropriate. What do you say as you slam your textbook shut? “I have finished my homework!” What so you say at supper an hour later when your parents ask yo about your homework? “Yup, I finished it.”
Past perfect: it took a while and ended in the past.
I thought I had been a diligent student, but then I met Don.
Lara had never been to A large department store until she came to the US.
Progressive. That’s the tense with ‘ing. It means that the action is still happening, or was still happening when something else happened.
He was singing operatically to himself when I came home.
I had been singing for two hours when you came home.
I have been hoping that you don’t mind if I sing in private.
Of course you can think of piles of examples, good and bad, and you can be alert for them as you read. Maybe you have an example to share in the comments. If you think about it for several minutes, you will have been about to make a comment before you actually did so. (That’s future perfect periphrastic, which we won’t get into.)
And since I didn’t copy the web page I got the NASA sentence from, here’s another NASA photo:
And for you guys who were hoping for a girlie picture, I created this link. It’s a picture of an astronette.