public static function cutForSearch($sentence, $options = array())
    {
        $defaults = array(
            'mode'=>'default'
        );

        $options = array_merge($defaults, $options);

        $seg_list = array();

        $cut_seg_list = Jieba::cut($sentence);

        foreach ($cut_seg_list as $w) {
            $len = mb_strlen($w, 'UTF-8');

            if ($len>2) {
                for ($i=0; $i<($len-1); $i++) {
                    $gram2 = mb_substr($w, $i, 2, 'UTF-8');

                    if (isset(self::$FREQ[$gram2])) {
                        array_push($seg_list, $gram2);
                    }
                }
            }

            if (mb_strlen($w, 'UTF-8')>3) {
                for ($i=0; $i<($len-2); $i++) {
                    $gram3 = mb_substr($w, $i, 3, 'UTF-8');

                    if (isset(self::$FREQ[$gram3])) {
                        array_push($seg_list, $gram3);
                    }
                }
            }

            array_push($seg_list, $w);
        }

        return $seg_list;
    }