In English, the verb must agree with the grammatical subject in person (first, second, or third) and in number (singular or plural).
For the verb work in the present tense, the verb form changes depending on the subject: "I work" and "he/she/it works".
This is known as subject-verb agreement.

Agreement is easy when the subject is clear and is placed next to the verb, as in the examples using ‘work’, but occasionally the writer can misidentify the subject or lose sight of it completely. In example 1a) the grammatical subject (in italics) is far from the verb (also in italics):

Incorrect:

1a) The enzymic activity of the polinaceous extracts from mature plants were higher than expected.

As the subject is in the singular, the verb must also be in the singular:

Correct version:

1b) The enzymic activity of the polinaceous extracts from mature plants was higher than expected.

A typical error:

This week’s photographs come a little later than usual but celebrates our lovely community.

In this sentence, the grammatical subject is ‘photographs’ in the plural and the writer has correctly put the first verb ‘come’ in the plural but later in the sentence, the second verb ‘celebrates’ is in the singular, making this ungrammatical. The grammatical subject and the verb must agree. Here are some contrastive examples between singular and plural:

Singular: This week’s photograph comes a little later than usual but celebrates our lovely community.

Plural: This week’s photographs come a little later than usual but celebrate our lovely community.

Singular: The analysis of the results shows that more research is needed.

Plural: The analyses of the results show that more research is needed.

Singular: The cutback introduced by the government has had an adverse effect on families.

Plural: The cutbacks introduced by the government have had an adverse effect on families.

Singular: Inflation is on the increase.

Plural: Inflation and increased interest rates are to be expected.