A:1321
B:2113
C:813
D:138
么明亮”。这句话说明( )
—Qian Xuesen,the Father of China's Missiles.He is the ______ of China.
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?