The sentence is, for example,

  • The researchers investigated and found that due to the rise of AI bots, most of the existing works have focused on protecting the email services from spam.

Is this structure considered wrong speaking of tense use?

  • No, it's fine. However, I'm flagging this as off-topic ("belongs on ELL"). Hi cpx, you may not be aware that our other site English Language Learners is the best place to look for answers on English questions that a fluent speaker would find trivial. If you have a question for ELL, be sure to read their guidance on what you can ask. :-) Dec 28, 2018 at 12:50
  • @Chappo: Thanks, I will delete it. But I just want to be clear that since researchers found the information in past, by using present perfect I am saying it is still relevant in present? Can you elaborate your comment on this?
    – cpx
    Dec 28, 2018 at 13:12
  • If what the researchers found is still correct (rather than some historic fact that has since become untrue), then present perfect correctly indicates that the past fact is presently true. Dec 28, 2018 at 13:18

1 Answer 1


The researchers investigated and found that . . .

This part of the sentence happened in the past. The concluding part of the sentence can talk about the past, present or future, relative to that point in time, and still be fine, so long as it is still true:

a) . . . robots had plotted to take over the world.
b) . . . robots are plotting to take over the world.
c) . . . robots will plot to take over the world.

So long as the statement has not been proven to be false in some way since the investigation occurred, the particular time frame is still valid.

For instance, if, many months later, robots are still plotting to take over the word, then b) remains an accurate statement.

This is in line with reported speech where, if the thing reported is still true, you do not need to backshift the tense—it can optionally remain in the present (or future):

Mary told me that she is sorry. (And she still is.)
Mary told me that she will be sorry in 2030. (A date still to come, when, as much as the future can be predicted, something will happen.)

If, however, the thing is no longer a true statement, then the tense should remain in the past—rather than refer to a present or future event or situation:

Mary told me that she was fine. (She has since died.)

Note: To be clear, there are many possible specific verb conjugations that can be used. The actual sentence from the question is perfectly fine.

  • Can you also include ". . . robots have plotted" in the answer?
    – cpx
    Dec 28, 2018 at 18:41
  • @cpx Yes, indeed. There are many variations of verb conjugations that could be used. I just picked a single one for past, present, and future. Dec 28, 2018 at 18:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.