$arr = array ( 0 => array ( 0 => 'question three', 'detail' => 'question three', ), 1 => array ( 0 => 'question four', 'detail' => 'question four', ), 2 => array ( 0 => 'question five', 'detail' => 'question five', ), );
$test = array(0 => 'question three', 'detail' => 'question three',);
if (in_array($test,$arr))
{
    echo 'yes';
}

------解决方案--------------------

foreach($var as $key=>$val){
	foreach($val as $k=>$v){
		if(in_array('c',$v)){
			echo "C";
		}else{
			echo "N";
		}
	}

}
不知道你的具体是什么样的数组，这样应该可以，你可以试试。