php – 将使用循环创建的数组附加到另??一个数组

$variables_a = array(
   'a' => $a,'b' => $b,'c' => $c
);

然后另一个$variables_b = array(‘x’,’y’,’z’)我想循环遍历B数组,如下所示：

foreach($variables_b as $var) {
    $variables_c[] = array($var => $$var);
}

然后合并A& C和$variables_combined = array_merge($variables_A,$variables_C)

我希望得到的输出是我print_r的时候

Array
(
     [a] => a
     [b] => b
     [c] => c
     [x] => x
     [y] => y
     [z] => z
)

但我得到的是

Array
(
     [a] => a
     [b] => b
     [c] => c
     [0] => Array
         (
            [x] => x
         )    
     [1] => Array
         (
            [y] => y
         )    
     [2] => Array
         (
            [z] => z
         )    
)

如果我将$feature_variables [] = array($feature => $$功能)更改为$feature_variables = array($feature => $$功能),我会得到

Array
(
     [a] => a
     [b] => b
     [c] => c
     [z] => z
)

即$variables_b中的最后一项,但没有其他项.那我哪里错了？