生死存亡的英文：
[Literal Meaning]
life/death/existence/extinction
(grave crisis between) life and death

[解释]
生存或者死亡。形容局势或斗争的发展已到最后关头。

[Explanation]
life and death

[例子]
农民起义军的势头越来越大，明朝已经到了生死存亡的关头。

[Example]
The power of the peasant rebels grew stronger and stronger, and the Ming Dynasty was at the moment of life and death.

It was as if the public and Congress felt the national peril instinctively and created a surrogate center.
好象公众和国会都本能地感受到国家的生死存亡，因而设立起一个代理中心。

That is a critical moment.
那是生死存亡的关头。