Select Case Mid(Hex, i, 1)
                Case "0" : B = B & "0000"
                Case "1" : B = B & "0001"
                Case "2" : B = B & "0010"
                Case "3" : B = B & "0011"
                Case "4" : B = B & "0100"
                Case "5" : B = B & "0101"
                Case "6" : B = B & "0110"
                Case "7" : B = B & "0111"
                Case "8" : B = B & "1000"
                Case "9" : B = B & "1001"
                Case "A" : B = B & "1010"
                Case "B" : B = B & "1011"
                Case "C" : B = B & "1100"
                Case "D" : B = B & "1101"
                Case "E" : B = B & "1110"
                Case "F" : B = B & "1111"
            End Select
这一段什么意思

switch(表达式)
{
case 常量表达式1:语句1;
....
case 常量表达式2:语句2;

}