下列化学变化过程中不涉及氧化还原反应的是 （ ）
A．氯碱工业
B．水玻璃制硅酸
C．工业制硝酸
D．海水中提炼镁
答案：B
She showed the visitors around the museum，the construction _______ had taken more than three years.[ ]
A．for which
B．with which
C．of which
D．to which
简述永久式封隔器的使用范围。
