This time next week, I ... on the beach.

The correct answer is "will be lying". Here's why: The sentence refers to a specific time in the future ("This time next week"). The correct tense to use here is the future continuous (also known as future progressive) tense, which is formed using "will be" + the present participle (verb ending in -ing). This tense describes an action that will be in progress at a specific time in the future. * will be lying: This is the correct future continuous tense. It indicates that the action of lying on the beach will be in progress at that specific time next week. * lie: This is the base form of the verb and doesn't fit the future context. * am lying: This is the present continuous tense, which refers to an action happening now. * will lying: This is grammatically incorrect. The auxiliary verb "be" is needed after "will" in the future continuous tense. So, the completed sentence is: "This time next week, I will be lying on the beach."