hello, I have searched Vowel Digraph on google ~

I even got a very lovely children's song about it ~ “ When Two Vowels Go Walking, The First One Does The Talking ~” I learned that ---Vowel Digraph ---- If two vowels are beside each other in a word or syllable, the first vowel is usually long while the second vowel remains silent. Examples of vowel digraphs are:
ai-- maid, ee-- sweet, ea--bean, oa---- boat, ay-----tray. This rule does not
apply to diphthongs.

they say Vowel Digraph are ----- ea ai oa ay ee .

My confusion is :

If ue oe ie could also view as vowel digraph ?

As follows :

oe toe shoe

ue blue glue true clue

ie tie pie lie die

I appreciate your help very much~Emotion: smile

Yes but "shoe" is pronounced to rhyme with "who".
oe toe shoe
This one doesn't work. Toe and shoe have different vowel sounds.

The other examples fit the first long vowel idea.
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thank you ,but how toe cant fit the first long vowel idea ?

isnt the o of toe sounds like the o of ohio or tokyo ?
 LouiseT's reply was promoted to an answer.