Look no further for a simple explanation of subject verb agreement, and examples.
Grammar checker will tell you, not very helpfully, that ‘the verb of a sentence must agree with the subject in number and in person’. What this means is that you’ve used the wrong version of the verb – the equivalent of, for example, ‘I is happy’ instead of ‘I am happy’. The error might be obvious in this example, but in longer and more complex sentences it can be harder to spot.
Take this sentence:
Gemma swims twice a week.
This is correct because the subject of the sentence (Gemma) agrees with the verb (swims). This is subject-verb agreement.
But what if we add more people?
Gemma and Jill swim twice a week.
The subject has changed ‘in number’, and the verb changes accordingly, to ‘swim’ (without an ‘s’on the end).
So when grammar checker says that the verb must agree ‘in number and in person’, what does that actually mean? Basically it’s a grammatical term, best explained in this table:
|1st||I swim||We swim|
|2nd||You swim||You swim|
|3rd||He/she/it swims||They swim|
Most verbs follow the same pattern – try filling in the table with the verbs to work, to eat, to love and so on.
In the example sentences above we can replace the subject either with ‘she’ (Gemma) or ‘they’ (Gemma and Jill). Then you just need to check that the verb still works.
When the subject isn’t so clear
Sometimes it isn’t so clear what the subject of the sentence is. Take this example:
The rise of the world wide web and social networking have led to a breakdown in family relationships.
This is wrong. The subject of the sentence is actually ‘the rise’ (singular, can replace with ‘it’) which doesn’t agree with the verb ‘have’. The sentence should read:
The rise of the world wide web and social networking has led to a breakdown in family relationships.
The best way to avoid this sort of error is to find a simpler noun to represent the subject. Perhaps:
The internet has led to a breakdown in family relationships.