php二维数组怎么增加键值

$listening_collect = $this->ser_toefllistening->zt_collect($listening_articleid)->result_array();
        foreach ($listening_collect as $key => $value){
            //变量值$answer是个数组 answer是里面的一个元素
            $answer = $this->ser_toefllistening->answer($value['id'],$u_id);
            $listening_collect[$key]['you_answer'] = $answer['answer'];
        }

//这个是一维数组添加
foreach($arr as $key => &$vo){
        $vo['name'] = '星星';
        $vo['age'] = '24';
    }
    $arr[$key]['name'] = '星星';
    $arr[$key]['age'] = '24';

$res = Db::name('ht_let_go')
            ->where("title", "like", "%$name%")
            ->order('id desc')
            ->paginate($size,false,['page'=> $page,'query'=>request()->param()])->toArray();


        foreach ($res['data'] as $k => $v){
            $res['data'][$k]['sum_num']  = Db::name('ht_let_go_buy')->where('let_go_id',$v['id'])->count();
        }
dump($res);die;