单项选择题
A．A historian. B．A government officer. C．A sociologist. D．An Educator.
A．UFO’s are only recent observations B．UFO sightings are not new C．UFO’s are just comets, and auroras etc. D．UFO’s are inventions by people who lack scientific knowledge
A．The Marines. B．The sailors. C．The soldiers. D．Mrs. L