In English, when two vowels are written together, you do not necessarily have to say both vowels. This is called a vowel digraph. One of the vowels is pronounced, the other is silent. This is the case in the word PAIN for the digraph AI which is pronounced as a long A while the I is silent. Sometimes, the vowel digraph is pronounced as a vowel sound that you would not expect. This is the case in the word VEIN with the digraph EI which is pronounced as a long A.
Long A can be spelled: AI (pain); AY (bay); EI (vein)
Long E can be spelled: EE (meet); EA (meat); EY (valley); IE (piece); EI (ceiling)
Long I can be spelled:
Long O can be spelled: OA (boat); OE (toe)
Long U can be spelled:
Long EW can be spelled: UE (revenue); OO (spoon); EW (flew); UI (suit)
Long OY can be spelled: OI (oil); OY (boy)
Long OW can be spelled: OU OW
Short o can be spelled: AU (saucer); AW (law)
Check out these examples:
Beat: B-long E-T
Feel: F-long E-L
Eight: Long A-T
New: N-Long EW
Oil: Long OY-L
Play: P-L-Long A