Parallelism

[gmatwork]

Do we need to have same tenses in parallel structures?

Let's say -

If the sentence has a structure - X ,and Y

Do X and Y need to have to have the same tense?

[davetzulin]

Do we need to have same tenses in parallel structures?

Let's say -

If the sentence has a structure - X ,and Y

Do X and Y need to have to have the same tense?

i'd also like clarification on this.

I've read in several posts and have seen in some OG questions errors when different tenses are used in a parallel elements.

as far as i know they should be.

[RonPurewal]

Do we need to have same tenses in parallel structures?

no. verb tenses are determined entirely by meaning/context. if the context implies the same timeframe for both verbs, then they should have the same tense; if the context implies different time frames, then the verbs can have different tenses.

here's a simple example:
Thomas joined the military in 1989 and will be discharged next year.
this is a parallel structure with two verbs (joined ... and will be discharged ...), but it should be obvious that the two verbs need different tenses.
(note also that the first verb is active, while the second is passive. that's also correct, and it's also determined completely by context.)

--

so, it's incorrect to think "parallelism means same tense". on the other hand, by the very nature of parallelism, it will very often describe two or more actions happening at the same time, in which case those verbs would appear in the same tense. so, if you really aren't sure, it may not be a bad way to guess -- although it's not 100 percent reliable, as i showed above.

[gmatwork]

Thanks for going an extra step and pointing out the active and passive issue as well.

So a parallel marker does not restrict parallel structures to have same voice, we can have some parallel elements with active and some with passive voice...but again that will depend on the requirement of the context.

[RonPurewal]

Thanks for going an extra step and pointing out the active and passive issue as well.

So a parallel marker does not restrict parallel structures to have same voice, we can have some parallel elements with active and some with passive voice...but again that will depend on the requirement of the context.

parallelism requires only that verbs be parallel to other verbs -- this is the extent of the grammatical issue. as always, tense and voice are entirely determined by context.

in MANY cases of parallelism, the tenses/voices will be the same. this is a result of the nature of parallelism -- usually, parallel structures describe things in very similar circumstances. however, it's easy to create counterexamples, such as the one above, in which different tenses/voices are parallel.

by the way, i have moved this thread to the correct folder. from now on, please take care to post these things where they belong.
thanks in advance.