导读：I'manounwithsixletters. Myfirstletterisin'nose',butnotin'rose'. Mysecondletteran...

I'm a noun with six letters. 

My first letter is in 'nose', but not in 'rose'. 

My second letter and third letter are the same. They're both vowel. You can find me among letters of 'a,e,i,o,u'. 

My fourth letter is in 'doctor', and is in 'study' as well. 

My fifth letter is in 'blackboard'. 

My last letter is also a vowel. 

I am a kind of food. 

Can you guess what I am?