A php statement, online help

A php statement, online help $ Start = "2 ";
$ Jieshu = "10 ";

$ Cmd = 'abc.exe-I 1.mp3-B 360-ar 24000-ss $ start-t $ jieshu 2. m4r ';
// How can I write the above sentence correctly? My start and jieshu operations cannot read the parameters? How can I write correctly?
?>

Reply to discussion (solution)

$ Cmd = 'abc.exe-I 1.mp3-B 360-ar 24000-ss. $ start-t. $ jieshu 2. m4r ';
I can't add a symbol in front of it...

$ Cmd = "abc.exe-I 1.mp3-B 360-ar 24000-ss. $ start-t. $ jieshu 2. m4r"; replace it with double quotation marks. Otherwise, it will not be parsed as the most variable.

The problem is not clearly described. What do you want to do?

Variable compilation with single quotation marks, compilation with double quotation marks, or adding {} to the variable outside {}