In the following text, should I replace the highlighted can't with couldn't?

Furthermore, the third point the lecture uses to contradict the passage is that organic foods don't benefit small famers. While the reading claims that organic foods allow small farmers to make high profits from their business, the professor in the lecture completely denies that idea. To support his belief he says that since 1982 small farmers can't make a living off of producing organic foods. That is because big companies always buy their foods; and the professor encourages us to buy any organic food and attempt to see the producer. He is sure that we won't see any small farmer's name. Consequently small farmers will continue to face economic problems in the future if they depend only on organic foods.

  • I have taken the liberty of correcting some errors of idiom and grammar which do not affect your question. If you do not like these edits you may roll back to your original version using the 'edit' link. Sep 7, 2013 at 11:21

1 Answer 1


A time expression headed by since defines a timeframe which extends from a point in the past up to the ‘Reference Time’, the time you are talking about. A time frame with this particular shape usually calls for a perfect construction. Since your paragraph is cast in the present tense, you are talking about the present, and you should employ a present perfect:

The professor says that since 1982 small farmers have not been able to make a living off of producing organic fooods.

  • Nice answer; +1. Personally I think "The professor says that since" is a misleading opening in this case; I'm expecting since to mean because until I keep reading and realize that's not the case. I would advise the OP to move things around a bit, to something like "The professor says that small farmers have not been able to make a living off of producing organic foods since 1982." (This has the added benefit of moving the "important" information (what they aren't able to do) ahead of the less important (since when they weren't able to do it)). But that's just my $0.02. :)
    – WendiKidd
    Sep 7, 2013 at 18:38

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