In English, the subject and the verb always agree. If the subject is singular, the verb must also be singular; the same rule goes for the plural.
X and Y
If the sentence has nouns linked by 'and', the verb will be plural, because it will refer to both.
X or Y
If the sentence has nouns linked by 'or', the verb will be singular, because it will refer to only one of them.
|Some helpful tips on how to avoid common subject verb errors.||Smrt English|
|Specific examples with advanced subject verb agreement.||Espresso English|
|Some collective nouns can be plural or singular.||BBC Learning|