某空瓶的质量为200g,盛满水后质量是1.2kg,若用这个瓶盛满某液体,液体和瓶的总质量是13.8kg,求这种液体的密度?
—Does the young man standing there ________ the company?
—No, the company is ________ his father.
下列关于自然灾害的周期性和不重复性的特点,说法正确的是( )