Jenny's teeth are not good, because she ____.
A:has a sweet tooth
B:has sweet tooth
C:have a sweet tooth
D:have sweet teeth
不同鸟类在飞动过程中的情景有下列四幅图,对它们解释错误的是( )
H+____; OH﹣____; CO32﹣____; Cl﹣____; SO42﹣____;NH4+____.
中华民族伟大民族精神的核心内容是( )