It is important to remember that “a” in whale is a long vowel.

I found that many young kids including my son often pronounce “L” as “O”.

1) 蘋果是 “Apple” 不叫 “愛泡”: Vowel “a” vs. “e”

2) 和 -cl_cl- : 發尾音L, M, N 的重要性及要領