选B
Continual conflict among city-states caused the eventual decline of Greek civilization.
城邦间不断的冲突导致了希腊文明最终的衰落.
consistent一致的,符合的.如：His action is always consistent with his words.
constant表示“稳定的”、“不断的”或“不变的”、“可靠的”表示持续和惯常的重现,往往没有变化.例如：
We’ve had constant rain for three days.雨连续下了3天.
He is constant in his determination.他的决心不变.
continuous不断延伸的,连续不断的,强调中间无间断.如：
There was continuous fighting on the frontier all day yesterday.昨天一整天,边境上战斗没有停止.
The aeroplane is capable of five days continuous flight.这种飞机可以连续飞行5天.
continual 经常用来指不时重复的动作（包括使人不快的动作）.常译为“不断的”、“连续的”,即认为没有止境,中间可有间歇.例如：
I can’t work with these continual interruptions.这样不断地打搅,我无法工作.
The noise of hammering was continual.锤打的噪音连续不断