Linking verbs, also known as copulas, connect the subject of a sentence to a complement (either a noun, pronoun, or adjective) that provides additional information about the subject.
Linking verbs do not show an action but rather a state of being or a condition of the subject. Common examples of linking verbs include “be,” “appear,” “seem,” “become,” “remain,” “feel,” “sound,” and “look.”
For example, in the sentence “The flowers are beautiful,” “are” is the linking verb that connects the subject “flowers” to the complement “beautiful.” Another example is the sentence “He seemed tired,” where “seemed” is the linking verb that connects the subject “he” to the complement “tired.”
When to avoid a linking verb
When writing an academic text, avoid linking verbs in the main clauses of a thesis statement and topic sentences that express the main idea of a body paragraph.
Benjamin L. Stewart 