无法避免的事情
something unpleasant that cannot be avoided
  Going bald is just a fact of life. 谢顶是无法避免的事情。 
 Unfortunately for you, exams are a fact of life.
 There's no point complaining about rising prices. They're a fact of life.
 Long waits at security checkpoints are a fact of life in this area.
 There may be some colleagues you find hard to get on with, but that's a fact of life.
 See also: fact