势如累卵: be in a very perilous position; hazardous [precarious] like a pile of eggs
存亡: live or die; survive or perish; survive and downfall 短语和例子生死存亡的斗争 a life-and-death struggle; 危急存亡之秋 at the critical juncture of life and death; 与阵地共存亡 defend one's position to the death
存亡危急: at the critical juncture of life and death; at stake