下列标记物不能用于标记抗体的是()
A．碱性磷酸酶
B．铁蛋白
C．HRP
D．同位素
E．清蛋白
参考答案：E
After decades of effort, the city is still trying to _____ how to stop smoking in public places.
A．try out
B．let out
C．figure out
D．run out
