肾衰竭需要立即医疗干预。

___Kidney failure requires immediate medical attention.

他捐了一个肾来挽救朋友的生命。

He donated a ___kidney to save his friend's life.

肾脏在过滤血液和产生尿液方面起着关键作用。

The ___kidney plays a crucial role in filtering blood and producing urine.