Final answer:
A verb conveys action, occurrence, or state in a sentence and requires a subject. Linking verbs connect the subject to a subject complement that identifies or describes it. Subject-verb agreement is essential for grammatically correct sentences.
Step-by-step explanation:
A verb is an essential part of a sentence that conveys action, occurrence, or state of being. Verbs can also introduce states or descriptions and are frequently accompanied by auxiliaries like "will" or "shall" forming a verb phrase. Verbs always require a subject, which is the person or thing conducting the action or being described.
There are also linking verbs, such as "seem," "look," "smell," "sound," and "become." Linking verbs are followed by subject complements that typically come in the form of noun phrases (NPs) or adjectives (adjs), which describe or identify the subject. A typical sentence structure would be: (subject)+(linking verb)+(subject complement).
The subject of a sentence indicates "who" or "what" the sentence is about, whereas the predicate contains the verb, expressing the action or state associated with the subject. Verb and subject agreement is crucial; a singular subject pairs with a singular verb, while a plural subject requires a plural verb.
In the sentences "To talk about poll numbers at this stage of the election is simply counterproductive" and "To ensure a full refund, you must also bring your receipt," the phrases starting with the infinitive "to" function as subjects, necessitating a singular verb.