Suppose we pass the modified ciphertext

$$

$$

$=$

$($

$$

$$

$,$

$...$

$,$

$$

$$

$$

$1$

$$

$,$

$$

$$

$$

$)$

C

$$

$=($IV$,...,$C

n$1$

$$

$$

$,$C

n

$$

$$

$)$ into the padding oracle, and it returns True.