Quote Originally Posted by Erin View Post

Now, using these examples, and applying them to the rules I mentioned at the beginning, we will notice that if we made a sentence, person would be the subject of the verb speak and words would be the object of the verb speak. Using this procedure, we can figure out whether should use the -ing or -ed form of a participle that modifies a noun. And that's it!!

Of course, this is easy when the vocab is easy, and we often get confused when we are using difficult vocab because we sometimes don't know whether something is the subject or the object of the verb, but this procedure that I have explained is the only sure way to get the right answer.

In our sentence here, which replaces times, and times is the object of determined, but it is the subject of differed.

In other words, we have something like this:

...somebody determined times...

but

times differed...

I know some of you have learned that we should only use the -ing form only for actions that are ongoing/in progress in the present, but that's simply not true. We do occasionally use them correctly for past actions that were ongoing/in progress.

Finally, everybody gets confused simply because the -ed form appears in the second one, making people think the -ed form should appear again when it's reduced. We need to realize that there is truly no connection (for our purposes here in GMATland, anyway !!!!) between the two; it's pure coincidence that each has the -ed form in it!!!

If you stick to the rules that I just wrote, you'll be okay.
Hi Erin,
OG #42. Scientists have recently discovered what could be the largest and oldest living organism on Earth, a giant fungus that is an interwoven filigree of mushrooms and rootlike tentacles spawned by a single fertilized spore some 10,000 years ago and extending for more than 30 acres in the soil of a Michigan forest.
correct answer is: extending rather than extended

Can I solve OG# 42 by using your method above?
Fungus here is the object: A fungus is spawned => reduced to "spawned"
Whereas, fungus here is the subject: A fungus extended => reduced to "extending"