纳洛酮：
A．激动阿片受体
B．阻断阿片受体
C．二者均有
D．二者均无
参考答案：B
He _____ still here till now when he was born in the city.[ ]
A. stayed
B. stays
C. was
D. was like
简述铸铁按介稳定系结晶和稳定系结晶在C点和S点结晶产物有什么不同？
