One rule which all English-speaking children learn at school is what some primary teachers call the 'magic e'. If you add 'e' to the end of a word, it changes the sound from a short vowel to a long one. For example: hat /hæt/ hate /heit/ nap /næp/ nape /neip/ A doubled consonant also indicates a short sound. lack /læk/ lake /leik/ tapping /tæping/ taping /teiping/ I can't think of many cases where an 'a' is pronounced /e/, other than certain one-off irregular words such as 'said' /sed/ and the past form 'read' /red/, which you just have to learn.