想知代表英文 字母的.......

A = alpha
B = beta
These are letters of Greece. Normally people uses these A, B, C, etc. to explain clearly the letter they want to say. For example if you receive a phone call from Mr. AB and he asks you to write down his name, he may say : My name is A for alpha, B for beta.
This kind of usage is even more common in the fields that need accuracy of the words.
But H = Hotel is not a Greece letter. It is as I mentioned above, a clearer explanation of the letter you want to say.
In fact nowadays people will use more simple words to do this , such as :
A for apple
B for boy
C for Charlie
D for Dog
And when they say this, they often say it in the following ways :
The pronouciation is : apple boy charlie dog, ABCD