Try, for example:
Code:
Sub Demo()
Application.ScreenUpdating = False
With ActiveDocument.Range
With .Find
.ClearFormatting
.Replacement.ClearFormatting
.Text = "[0-9]{1,4} [AB].[DC]."
.Replacement.Text = ""
.Forward = True
.Format = False
.Wrap = wdFindStop
.MatchWildcards = True
.Execute
End With
Do While .Find.Found
If Split(.Text, " ")(1) = "B.C." Then
.InsertAfter " (chinese year " & Split(.Text, " ")(0) + 2699 & ")"
ElseIf Split(.Text, " ")(1) = "A.D." Then
.InsertAfter " (chinese year " & Split(.Text, " ")(0) + 2698 & ")"
End If
.Collapse wdCollapseEnd
.Find.Execute
Loop
End With
Application.ScreenUpdating = True
End Sub
Note: You'll need to check the correct value to add for B.C. years vs A.D. years, since there was no 0 B.C./A.D.