5. There is no water left in the __________ well. (near)

The correct answer is "nearby." The completed sentence will read: "There is no water left in the nearby well."

Explanation: In this context, "nearby" functions as an adjective to describe the well. It indicates the location of the well in relation to something or someone else which is implied in the context (usually the speaker or listener). The word "near" is an adjective and can be used to describe proximity, but to properly fit into the sentence structure, "nearby" is the appropriate form because it also conveys the meaning of closeness and is commonly used in English to describe something that is close in distance. Therefore, using "nearby" specifies that the well is located close to where the speaker or listener is.