drone(s) – n. a type of small aircraft that flies without a pilot

commercial – adj. related to or used in the buying and selling of goods and services

sighting(s) – n. an act of seeing something or someone that is rarely seen or difficult to see

practice – n. the activity of doing something again and again in order to become better at it

conspiracy theories – n. theories that explain events or situations as the result of a secret plan by usually powerful people or groups

maintenance – n. the act of keeping property or equipment in good condition by making repairs or correcting problems

zone – n. an area that is different from other areas in a particular way

fleet – n. a group of ships or vehicles that move or work together or that are controlled or owned by one company

detect(ing) – v. to discover or notice the presence of something that is hidden or hard to see, hear, taste, feel or smell
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