—This morning your mobile phone was always busy. I couldn’t ________ to you until several attempts.

—Oh, I’m sorry. I was discussing the price of our products with a client over the phone.

A．get over

B．get through

C．get across

D．get on

气-液色谱柱中，与分离度无关的因素是：（）

A、增加柱长；

B、改用更灵敏的检测器；

C、调节流速；

D、改变固定液的化学性质。