在发生事故危险或接到紧急停车信号时，都必须()。
A、及时停车
B、停午
C、紧急停车
参考答案：C
______her ambition of becoming a professional singer, she has been training very hard since an early age.
A．Realizing
B．To realize
C．Having realized
D．To have realized
主诉牙应诊断
A．根尖囊肿
B．慢性牙髓炎
C．慢性牙周炎
D．根尖肉芽肿
E．慢性牙槽脓肿
