D-His hours <u>are </u>long and busy. This is the sentence in which the verb is a linking verb. See the underlined word. " To be" is the verb. This is a linking verb because it <em>links </em>or connects the subject: <em>His hours</em> with the adjectives from the predicate: <em>long and busy</em>. The verb "to be" has no meaning by itself. If we put a question to the sentence to get " to be " as an answer, we will ask: What<em> are </em>his hours like?. The answer will not focus on " to be" but on " His hours". Compare with the following:
A- He <u>works</u> at a gas station. The verb " to work" has meaning by itself. We can ask a question to get " works" as an answer: What does he do at the gas station? Therefore, "To work" does not link parts of the sentence , it just tells what a person does. It is a dynamic verb performed by a pesron.
B. His boss <u>pays </u>him well. "To pay" has its own meaning and it can be the answer to: What does his boss do to him? A person pays to somebody. This is also a dynamic verb performed by people.
C. He has <u>walked</u> to work from his house. " To walk" is also a dynamic verb; it has got meaning by itself and it can be the answer to: How has he got to work from his house?