Which of the following sentences contains a linking verb?

• A. The sky is blue.
• B. The class are working on their science project.
• C. The leaves look green.
• D. The cake was baked yesterday.

Answer: (A)

A linking verb connects the subject to information about it, usually a description or identity, rather than showing action. In this sentence, the word is is a form of to be that links the subject The sky to the descriptor blue. It tells us what the sky is like, not what the sky does, which is exactly what a linking verb does. The others revolve around action or different verb forms, such as describing ongoing activity or forming a passive construction, rather than linking the subject to a description.