水火的英文：
extreme misery; fire and water; two things incompatible

参考例句：

When still very young, Bocheng was already determined to deliver the people from their abyss of suffering.
伯承从青少年时代起就立志“拯民于水火”

extreme是什么意思：
adj. 末端的；极端的；急进的；偏激的
n. 极端；末端；最大程度

in an extremity
智尽力竭|陷入绝境

relative extreme
相对极值

It is extremely corrosive.
它是极强的腐蚀剂。

misery是什么意思：
n. 悲惨，不幸；穷困；痛苦

You old misery!
你这个爱抱怨的老家伙！

Misery makes strange bedfellows.
患难时不择友。

very unhappy; full of misery.
非常不高兴；充满的痛苦。

fire是什么意思：
n. 火；炉火；火灾；热情；激情；磨难；炮火
v. 点燃；烧制；烘制；激励；充满激情；解雇；着火；开枪

The fire raged.
大火熊熊燃烧。

They fired at the robbers.
他们向强盗开枪。

The house was on fire.
房子起火了！