以下是替换字符串中制定字符的函数过程： Function sReplace (SearchLine As String，SearchFor As String，Replace With As String) As String Dim vSearchLine As String，found As Integer found=InStr (SearchLine，SearchFor)：vSearchLine=SearchLine If found ＜＞0 Then vSearchLine=" " If found＞1 Then vSearchLine=Left (SearchLine，found -1) vSearchLine=vSearchLine+ReplaceWith End If If(表达式)＜Len(SearchLine)Then vSearchLine=vSearchLine+Rights (SearchLine，Len (SearchLine) ―found―Len(SearchFor)+1) End If End If sReplace=vSeachLine End Function过程中的“表达式”应为( )。