Meaning: 'Throughout' means in every part of a place or during the whole of a period.

Wrong options:

• along: The word 'along' suggests a linear direction or proximity, which does not convey the idea of coverage across the entire country as 'throughout' does.
• allow: 'Allow' is a verb that does not fit grammatically in this context, as it does not serve as a preposition to indicate location.
• give: 'Give' is a verb that does not relate to the context of location and does not fit grammatically in this sentence.
• left: 'Left' is the past participle of 'leave' and does not function as a preposition, making it unsuitable here.
• seen: 'Seen' is the past participle of 'see' and does not fit grammatically or contextually as it does not indicate location.

Correct answer: allow

Explanation: The verb 'allow' fits grammatically as it indicates the action of permitting the artificial flooding to occur. It is necessary for the sentence structure and conveys the intended meaning of enabling the flooding process.

Meaning: 'Allow' means to permit something to happen or to give permission for something.

Wrong options:

• throughout: 'Throughout' is a preposition that does not fit grammatically as it does not convey an action of permitting.
• drought: 'Drought' is a noun that does not fit in this context as it does not indicate an action or permission.
• left: 'Left' is the past participle of 'leave' and does not function as a verb to indicate permission.
• give: 'Give' is a verb that does not convey the specific meaning of permitting in this context.
• seen: 'Seen' is the past participle of 'see' and does not fit grammatically or contextually as it does not indicate an action.

Correct answer: left

Explanation: The word 'left' serves as the past participle of 'leave,' indicating what happened to the buildings after the towns were relocated. It fits grammatically and contextually as it describes the state of the buildings that remain.

Meaning: 'Left' means to have been abandoned or to remain after others have departed.

Wrong options:

• throughout: 'Throughout' is a preposition that does not fit grammatically as it does not describe the state of the buildings.
• allow: 'Allow' is a verb that does not fit in this context as it does not describe the condition of the buildings.
• drought: 'Drought' is a noun that does not relate to the state of the buildings and does not fit grammatically.
• give: 'Give' is a verb that does not convey the meaning of abandonment or remaining.
• seen: 'Seen' is the past participle of 'see' and does not fit grammatically or contextually as it does not describe the state of the buildings.

Correct answer: drought

Explanation: The term 'drought' fits grammatically as a noun that describes a prolonged period of abnormally low rainfall, which is relevant to the context of water levels in reservoirs. It logically connects to the preceding sentence about water problems.

Meaning: 'Drought' refers to a prolonged dry period with insufficient rainfall, impacting water supply.

Wrong options:

• allow: 'Allow' is a verb that does not fit grammatically or contextually as it does not describe a condition related to water levels.
• throughout: 'Throughout' is a preposition that does not fit as it does not describe a state or condition.
• left: 'Left' is the past participle of 'leave' and does not fit as it does not describe a condition related to water levels.
• give: 'Give' is a verb that does not relate to the context of water levels and does not fit grammatically.
• seen: 'Seen' is the past participle of 'see' and does not fit grammatically or contextually as it does not describe a condition.