many years(plural)

• 多年以来

  for many years

• 多年以前

  many years ago

• 多年以后

  years later

• 多年的友谊

  many years of friendship

• 多年的老朋友

  old friends of many years standing

• 多年劳动的成果

  the fruit of years of hard work

• 多年不见了！

  It's been years!

• 我和他多年不见了。

  I haven't seen him in years.

• 多年没有音信

  no news for years