如何在PHP中删除这些语法错误？

I want to remove syntax error from a php script file. After hour of checking i could not remove them, How could be these identified?

1st one is Parse error: syntax error, unexpected ')' on second line of below code:

require( "./sources/misc/classes.php" );
    ( );
    if ( file_exists( "./sources/sql/sql.php" ) )
    {
        require( "./sources/sql/sql.php" );
    }
    else
    {
        header( "Location: install/" );
    }

And also it gives error on line on as Parse error: syntax error, unexpected '[' on first line of below code:

if ( [$FORM['ajax']]isset( $FORM['ajax'], $aj ) )
{
    require( "./sources/{$FORM['ajax']}.php" );
    ( );
    $base->$FORM['x']( );
}

Will you help me identify and understand errors? and Why they come?

remove those lines of code with ....

( );

AND

if ( [$FORM['ajax']]isset( $FORM['ajax'], $aj ) )

should be

if (isset( $FORM['ajax'], $aj ) )

... and this is dangerous, never trust user input ... here: user might include files you don't want to be included!

require( "./sources/{$FORM['ajax']}.php" );

PHP does not like empty expressions like ();

Remove that and you should be fine.

First one..

require( "./sources/misc/classes.php" );
    //( );
    if ( file_exists( "./sources/sql/sql.php" ) )
    {
        require( "./sources/sql/sql.php" );
    }
    else
    {
        header( "Location: install/" );
    }

second

if (isset($FORM['ajax'], $aj))
{
    require( "./sources/" . $FORM['ajax'] . ".php" );
    //( );
    $base->$FORM['x'];//( );
}