John and I＿＿friends for eight years. We first got to know each other at a Christmas   party. But we＿＿ each other a couple of times before that.

A．had been； have met

B．have been； have met

C．had been； had met

D．have been； had met

火场逃生原则基本上可用十六个字来说明。即：确保安全，迅速撤离，顾全大局，救助结合。