A 1972 agreement between Canada and the United States reduced

This one is a cruel classic that forces you to think really, really carefully about the connection between verb tenses and the intended meaning of the sentence. We covered this one at the end of our webinar on GMAT verb tenses, so head over there if you prefer your explanations in video form.


(A) is awfully tempting. The agreement happened in the past (1972), so it’s reasonable enough to use “reduced” here.

But what about the use of past perfect tense (“had been allowed to dump”)? Whenever you see the past perfect tense, it has to describe an action that is completed in the past, but BEFORE some other “time marker” in the past – usually another action in simple past tense. And we do have another action in simple past here: “reduced the amount of phosphates.” Superficially, this looks good.

But those verb tenses don’t actually make sense! Literally, (A) is saying that the 1972 agreement “reduced the amount of phosphates that municipalities had been allowed to dump” – meaning that the 1972 agreement changed the amount that municipalities had been allowed to dump BEFORE the agreement went into place. And that makes no sense: how could a 1972 agreement reach even further into the past to change municipalities' behavior?

It’s subtle. And cruel and difficult. And if you wanted to be conservative on your first pass through the answer choices, you certainly could hang onto (A). But as you’ll see in a moment, we definitely have a better option.


(B) is an even worse version of (A). How can the 1972 agreement reach back into the even-more-distant past to change the amount that “municipalities had been dumping”? Plus, there’s no good reason to use the progressive tense here, and the phrase “phosphate amount” strikes me as being awfully weird.

But the logic of the sequence of actions is the real problem, just as it is in (A). So (B) is out, too.


There are all sorts of little problems with this one. First, I don’t think it’s ideal to say that the 1972 agreement “reduces” the phosphate amount. The agreement reduced that amount when it took effect in the past – so it’s hard to argue that the present tense would work here.

Second, the phrase “phosphate amount” still strikes me as weird. I’m not certain that it’s 100% wrong, and I wouldn’t eliminate (C) solely because of it. But “the amount of phosphates” is clearly better.

Finally, I don’t understand why we would use the present perfect “have been allowed to dump” in this sentence, particularly since it’s accompanied by the present tense “reduces.” “Have been allowed” suggests that the action started in the past and continues in the present. So the sentence is literally saying that municipalities “have been allowed” to dump a certain amount beginning in the past, but only because of a 1972 agreement… which “reduces” that amount only in the present? That doesn’t make sense.

So (C) is out.


I know: this one doesn’t sound great. Why are we mixing the past tense with the present tense in this particular case? Superficially, it just doesn’t seem right.

But keep in mind that the simple present tense in English just describes a general characteristic. If we say “Mike surfs like a champion”, that doesn’t necessarily mean that Mike is surfing right now; it just means that he has the general characteristic of surfing like a champion.

So in this case, “the amount of phosphates that municipalities are allowed to dump” is completely fine: it’s a general statement of how much the municipalities can dump. And back in the past – specifically in 1972 – the agreement reduced that amount to its current levels. So the past tense “reduced” makes sense, and so does the present tense “are allowed.”

It might make us squirm a bit, but we have no reason to eliminate (D).


Again, “reduces” doesn’t make a lot of sense here, for the same reasons as we mentioned in answer choice (C). Plus, what the heck is going on with the phrase “allowed for dumping by municipalities”? This is a weird passive construction, and it’s far less clear than “municipalities are allowed to dump.”

So (E) is out, and (D) is the best we can do.