一个关于数组循环的有关问题

$array = array ('A' => 'a', 'B' => 'b', 'C' => 'c', 'D' => 'd', 'E' => 'e', 'F' => 'f', 'G' => 'g', 'H' => 'h', 'I' => 'i', 'J' => 'j', 'K' => 'k', 'L' => 'l', 'M' => 'm', 'N' => 'n', 'O' => 'o', 'P' => 'p', 'Q' => 'q', 'R' => 'r', 'S' => 's', 'T' => 't', 'U' => 'u', 'V' => 'v', 'W' => 'w', 'X' => 'x', 'Y' => 'y', 'Z' => 'z' );

		
			
				
A
				
B
				
C
				
D
				
E
				
F
			
			
				
a
				
b
				
c
				
d
				
e
				
f
			
			
				
G
				
H
				
I
				
J
				
K
				
L
			
						
				
g
				
h
				
i
				
j
				
k
				
l
			
			
				
M
				
N
				
O
				
P
				
Q
				
R
			
			
				
m
				
n
				
o
				
p
				
q
				
r
			
						
				
S
				
T
				
U
				
V
				
W
				
X
			
			
				
s
				
t
				
u
				
v
				
w
				
x
			
			
				
Y
				
Z
				
				
				
				
			
				
				
y
				
z
				
				
				
				
			
		
	

$array = array ('A' => 'a', 'B' => 'b', 'C' => 'c', 'D' => 'd', 'E' => 'e', 'F' => 'f', 'G' => 'g', 'H' => 'h', 'I' => 'i', 'J' => 'j', 'K' => 'k', 'L' => 'l', 'M' => 'm', 'N' => 'n', 'O' => 'o', 'P' => 'p', 'Q' => 'q', 'R' => 'r', 'S' => 's', 'T' => 't', 'U' => 'u', 'V' => 'v', 'W' => 'w', 'X' => 'x', 'Y' => 'y', 'Z' => 'z' );

for($i=0; $i  echo '', PHP_EOL;
  $t1 = array_keys(array_slice($array, $i, 6)) + array_fill(0, 6, '');
  $t2 = array_values(array_slice($array, $i, 6)) + array_fill(0, 6, '');
  foreach($t1 as $v) {
    echo "  $v", PHP_EOL;
  }
  echo '', PHP_EOL;

  echo '', PHP_EOL;
  foreach($t2 as $v) {
    echo "  $v", PHP_EOL;
  }
  echo '', PHP_EOL;
}

  A
  B
  C
  D
  E
  F


  a
  b
  c
  d
  e
  f


  G
  H
  I
  J
  K
  L


  g