(____) It's so big!
(____) It has a short tail.
(____) It's an elephant.
(____) It has a long nose.
(____) It has big ears.
按照玻尔理论,一个氢原子中的电子从半径为ra的圆周轨道上自发地直接跃迁到一个半径为rb的圆周轨道上,ra>rb,在此过程中( )
下列仪器能直接在酒精灯火焰上加热的是 ____ .
A.试管 B.集气瓶 C.量筒 D.____