    <?php
    $words = array("A", "BARK", "BOOK", "TREAT", "COMMON", "SQUAD", "Confuse");

    function canMakeWord($word) {
        $word = strtoupper($word);
        $blocks = array(
                "BO", "XK", "DQ", "CP", "NA",
                "GT", "RE", "TG", "QD", "FS",
                "JW", "HU", "VI", "AN", "OB",
                "ER", "FS", "LY", "PC", "ZM",
        );

        foreach (str_split($word) as $char) {
            foreach ($blocks as $k => $block) {
                if (strpos($block, $char) !== FALSE) {
                    unset($blocks[$k]);
                    continue(2);
                }
            }
            return false;
        }
        return true;
    }

    foreach ($words as $word) {
        echo $word.': ';
        echo canMakeWord($word) ? "True" : "False";
        echo "\r\n";
    }