English as a Second Language/Subject-verb agreement


QUESTION: Dear Shannon,
Welcome Back! I hope you are fine!
I read this sentence but I am not quite sure whether the verb (don't) is correctly used: "18% of the world's population don't have safe drinking water...". Isn't "18%" the subject? Should the verb be "doesn't"?

Also, I read "Around two-thirds (2/3) of a person's body weight is water". So, why "is" is used here and not "are"?

Lastly, "Ten years make up a decade". Mustn't is be "makes"?

Thanks for your continuous guidelines.

Best regards,
Antoine Ghannoum

ANSWER: #1: That's right, it should be "doesn't," but not for the reason you're thinking.  If we had said "18% of people," it would be "don't."  See explanation below.

#2: I'll quote someone else who said it best: "When a “fraction + of + noun” structure is the subject of a sentence, the verb is singular when it is a fraction of a single thing; but the verb is plural when it is a fraction of a number of things.

Rule: With words that indicate portions—some, all, none, percent, fraction, part, majority, remainder, and so forth —look at the noun in your of phrase (object of the preposition) to determine whether to use a singular or plural verb. If the object of the preposition is singular, use a singular verb. If the object of the preposition is plural, use a plural verb.

A fraction of a percentage can be singular or plural depending on how it is used: If a fraction or a percentage is followed by a phrase, the number of the noun in the phrase determines the number of the verb.
Twenty-five percent of the loan was re-invested.
(Loan is singular; the verb is singular.)
A third of the men are employed.
(Men is plural.)
Some, all, or most can be singular or plural, depending on the way they are used. They are singular when they refer to a quantity of something. They are plural when they refer to a number of things. Again, it is the noun in the intervening phrase that determines the number of the verb." -- [User "Ushuaia", http://forum.wordreference.com/showthread.php?t=1561638]

#3. No.  If you wrote it the other way around, that would be ok: A decade makes up ten years.  But in this case, Ten years is the subject.

---------- FOLLOW-UP ----------

QUESTION: Thanks a lot for your explanation.
Just a little comment on #3. The reason why I think "ten years makes (not 'make') up a decade" is that (as I remember) when we refer to 'ten years' as a period of time, then the verb should be singular. Again, I need your guideline.

Possibly.  I'm checking one of my grammar references, and we would say "A young couple were arguing about politics" because the meaning of couple is plural, although grammatically it is singular.  To me, it still seems that "ten years" isn't considered a collective noun and would be counted out as 10 individual years that later comprise a single idea (decade).

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Shannon Cole


I can answer questions related to learning the English and Spanish language.


I have taught ESL and Spanish since 1998 at the university and middle school levels. I am a native of the U.S., and have taught in both the U.S. and Mexico.

I am owner and operator of www.coleinstitute.com, an online language school.

Georgia TESOL in Action (1999)

B.A. in Spanish; M.Ed. in Language Education

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