— Could you please tell Peter that I want to talk to him?

— Sure, I will let him know as soon as he             back. [ ]

A. comes

B. came

C. has come

D. will come

一轻质弹簧原长10cm，甲乙两人同时用100N的力在两端反向拉弹簧，其长度变为12cm，若将弹簧一端固定，由甲一人用100N的力拉，则此时弹簧长度为（）cm，此弹簧的劲度系数为（）N/m。