collective-nounsgrammatical-numberverb-agreement
I've recently read a blurb from a local paper that included the following:
The pair was drinking prior to the shooting.
To me, this appears wrong and I would say that the proper way to make the statement would be:
The pair were drinking prior to the shooting.
Is the original article correct?
From Ngrams, you can see that "couple were married" beats "couple was married". This is especially true for British English.
Looking at the Ngram results for American and British English, while both forms are currently used roughly equally often in the U.S., hardly anybody says "the couple is getting married" in the U.K.
When referring to amounts of objects as opposed to the objects themselves, you normally use singular agreement. This has nothing to do with fractional amounts, and nothing to do with the use of 'a total of', but is a property of amounts in general.
- 40 litres of water was/*were poured into the tank.
- (A total of) 0.0605 moles (3 s.f.) of NaOH was/*were originally added to the aspirin.
We can see this when use anaphora to refer to the amount.
- 40 litres of water was poured into the tank. It/*They filled it to the brim.
- John weighs 200lbs. It is too much for his height./*They are too much for his height.
As TimLymington points out in the comments, there are some interesting wrinkles in this, although they simply confirm the statement above. Fractions always control plural number within the noun phrase, but whether that noun phrase will control plural verbal agreement depends on whether it refers to a measure or the objects themselves. So in the example below, plural agreement is used (not singular) because the noun phrase "0.5 apples" refers to actual apples and not to a measure.
- 0.5 apples were added to the mixture.
We can see this more clearly with the following examples, which don't use fractions.
- 30 lbs of potatoes were/?was peeled for the banquet.
- 30 lbs of potatoes is/*are not enough to feed this crowd.
In the first example, we are referring to the actual potatoes, and so the agreement is plural. Singular is marginally possible if we are referring to the measure. In the second example we are referring to the measure, and agreement is singular.
Best Answer
It's really just a matter of style.
Here's an NGram showing that both forms occur about as often. More recent prescriptive grammarians tend to say that a pair must be singular, but that's not going to stop half the English-speaking world from continuing with what was originally the much more common pluralised usage.
The most sensible way to approach this one is to assume both forms are valid. If the usage primarily deals with the pair as a unit, go for the singular. I don't find it easy to visualise a pair drinking together as anything other than two actual people, so in OP's example I would use the plural without hesitation.
By way of support for that last sentence, there aren't enough written instances in Google Books to compare usage for "pair ... drinking", but compare the 4,990 results for "pair were sitting" against 417 for "pair was sitting". The "guesstimate" figures aren't exactly true - when I page through them, GB admits the plural version has only 320 hits. But the singular really has only 79, which is still more than 4:1 in favour of using the plural if the verb implies each individual member of the pair doing something (particularly, people), as would be the case with, say, drinking.