Sub 甲烷下標()
'
' 甲烷下標 宏
'
'Selection.Find.ClearFormattingSelection.Find.Replacement.ClearFormattingWith Selection.Find.Text = "CH4".Replacement.Text = "CHguoshao4".Forward = True.Wrap = wdFindContinue.Format = False.MatchCase = False.MatchWholeWord = False.MatchByte = True.MatchWildcards = False.MatchSoundsLike = False.MatchAllWordForms = FalseEnd WithSelection.Find.Execute Replace:=wdReplaceAllSelection.Find.ClearFormattingSelection.Find.Replacement.ClearFormattingWith Selection.Find.Replacement.Font.Superscript = False.Subscript = TrueEnd WithWith Selection.Find.Text = "guoshao4".Replacement.Text = "4".Forward = True.Wrap = wdFindContinue.Format = True.MatchCase = False.MatchWholeWord = False.MatchByte = True.MatchWildcards = False.MatchSoundsLike = False.MatchAllWordForms = FalseEnd WithSelection.Find.Execute Replace:=wdReplaceAll
End Sub

思路是將CH4替換為CH和一個特殊的文字，然后將這個特殊的文字，替換為下標的4。PS：CH4中的CH忽略大小寫，均會被替換為大寫的CH。