Rather than thinking about spellings groups for vowels, think about vowel groups, words that belong to one single vowel sound.

与其考虑元音的拼写组，不如考虑元音组，即属于一个元音的单词。

And rather than thinking about spellings groups, in terms of vowels, so you ignore the spellings for the vowels is what I'm talking about.

对于元音而言，不要去看拼写组合，我是说，判断元音发音要忽视单词拼写。