Q:

It is the best thing that the government has done in a long time. 

• 1
  It is the best thing that was being done by the government in a long time.
• 2
  In a long time the best thing done by the government has been this.
• 3
  It is the best thing that has been done by the government in a long time.
• 4
  In a long time the best thing done by the government would be this.