I _____ his telephone number. Had I known it, I would have rung him up.

A．don’t known

B．didn’t know

C．hadn’t known

D．haven’t known

在传感器及检测系统的静态特性指标中，表达其对输入量变化的反应能力的是（）。

A、量程

B、重复性

C、灵敏度

D、线性度