subject-verb agreement when 'amount' is used


Even a small amount of gases have / has a large effect.

This sentence is an exerpt from a reading passage, which is talking about CO2 in global warming. It says CO2 accounts for only 0.038% in the atmosphere, and then the example sentence 'Even a small amount of gases have / has a large effect.' appears.

  • Which is the most appropriate answer?

    1. If gases is the subject, and it is plural, the correct answer would be 'have'.

    2. If the subject is a small amount, then the answer would be 'has'.

What do we see as the subject here? Can both be the subject?


Posted 2016-06-28T00:38:58.600

Reputation: 41

@Chappo There is absolutely nothing wrong in asking for help with work on here so long as you clearly identify what aspect of the work is confusing you and causing you problems. Please delete your comment as it could mislead readers. Thanks. – Araucaria - Not here any more. – 2016-06-28T15:23:51.193

@Chappo The comments above are correct. A proofreading question is a question like "please proofread the following paragraph". This question is not like that. – MetaEd – 2016-06-28T15:42:37.793

1@Mari-LouA, MετάEd, Chappo: Shall we all delete our comments here? – Araucaria - Not here any more. – 2016-06-29T23:56:04.550



The subject can only be amount, since gases is part of a prepositional phrase describing amount. The number of the verb's going to follow the number of the subject, hence it should be singular has.


Posted 2016-06-28T00:38:58.600

Reputation: 169

Correct. The key point is that the object of a preposition is never the subject of a sentence. The verb must match the subject. – MetaEd – 2016-06-28T15:56:43.440

@MετάEd Almost never, because there are troublesome beasts like a number of to prove the rule. – Araucaria - Not here any more. – 2016-06-29T19:42:19.147

@Araucaria Thank you for your answer. And your example 'a number of~' was the very thing that I was wondering about. Could you tell me what makes the difference between the two? Or should I just understand the case 'a number of ~' as an idiom? Thank you again for your answer. – VCCine – 2016-06-29T23:43:11.323

1When it comes to phrases with the word number, the rule is that the number is always singular, while a number is always plural. – Nick – 2016-06-29T23:50:05.223

Sorry, VCCine, I'm mega-busy right now (I''m in trouble!), but maybe @MετάEd will help you with this one :) [nudge, nudge MετάEd!] – Araucaria - Not here any more. – 2016-06-29T23:51:01.947

@Nick Yes +1 :) Nice point. – Araucaria - Not here any more. – 2016-06-29T23:54:05.697


In written English, the formal subject of the sentence (here, amount) will almost always be referenced and grammatical agreement/concord requires has.

The same is true for spoken English. However, it is possible that some speakers might say have because of the proximity of the word gases. This does not make gases the subject.

In short, use has.

Alan Carmack

Posted 2016-06-28T00:38:58.600

Reputation: 11 630