当电梯采用（）控制方式时，厅外召唤信号可顺向截梯
A.手柄操纵
B.按钮
C.信号
D.变频
参考答案：C
—Do you practice how to escape from dangers every term?
—Of course. Our school pays much attention to the ______ of safety.
A．development
B．importance
C．advertisement
D．difference
原子吸收分析过程中，干扰类型有哪些？如何抑制？
