Final answer:
The statement is false. Subject-verb agreement depends on the actual subject. Even if a sentence starts with 'it' as an expletive, the verb must agree in number with the true subject.
Step-by-step explanation:
The assertion that if a sentence begins with the expletive 'it', the verb is always singular even if the subject that follows the verb is plural, is false. While it is true that expletive constructions often use the pronoun 'it' as a placeholder, the verb should still agree in number with the true subject of the sentence. For instance, 'It is the boys who are making that noise.'
Verb agreement can become more complex with compound subjects. When two subjects are joined by the conjunction 'and' and form a compound subject, a plural verb is typically used. However, there are exceptions when the compound subject is treated as a single entity, in which the verb would be singular. The rule of thumb is that subject-verb agreement is determined by the actual subject(s) of the sentence, regardless of whether the sentence begins with an expletive 'it'.