php二维数组排列组合

 Array(    [0] => Array        (            [0] => m            [1] => n        )    [1] => Array        (            [0] => a            [1] => e        )    [2] => Array        (            [0] => he            [1] => hu            [2] => huo        )    [3] => Array        (            [0] => b        ))

希望的结果

 array(    [0]    =>  m,a,he,b    [1]    =>  m,e,he,b    [2]    =>  m,a,hu,b    [3]    =>  m,e,hu,b    [4]    =>  m,a,huo,b    [5]    =>  m,e,huo,b    [6]    =>  n,a,he,b    [7]    =>  n,e,he,b    [8]    =>  n,a,hu,b    [9]    =>  n,e,hu,b    [10] => n,a,huo,b    [11] => n,e,huo,b)

m,a,he,b
....
....
这些值得顺序不能变

求解