请教下正则多行模式与单行模式捕获的结果又啥区别

1. 简单匹配多行
-------------------------------------------------
    Set re1 = New regExp
        re1.Global = true
        re1.IgnoreCase = true
        re1.Multiline = false
    
        re1.Pattern = "\[code\]([\s\S]+)\[\/code\]" 
        str = re1.Replace(str,"$1")
        
    set re1=nothing
2. 对匹配到的内容进行相关操作
-------------------------------------------------
    Set re1 = New regExp
        re1.Global = true
        re1.IgnoreCase = true
        re1.Multiline = true            re1.Pattern = "\[textarea\]([?:\s\S]+)\[\/textarea\]"  
        Set Matches = re1.Execute(str)
            for each match in Matches
                match=replace(match,"<br/>",chr(13))
                match=replace(match,"&nbsp;",chr(32))
                match=replace(match,"&lt;","<")
                match=replace(match,"&gt;",">")
                match=replace(match,"&#39;","'") 
                match=replace(match,"&#34;",chr(34)) 
                match=replace(match,"[textarea]","<textarea name=""textarea"" cols=""60"" rows=""10"">",1,-1,1)
                match=replace(match,"[/textarea]","</textarea><br/><input type=""button"" onclick=""rc()"" value=""running code"" />",1,-1,1)
                
                re1.Pattern = "\[textarea\][\s\S]+\[\/textarea\]"  
                str = re1.Replace(str,match)
            next
    set    re1=nothing
-------------------------------------------------是不是单行模式不能捕获<br>这些的  如上面的例子