Reza: Spoken English and written English, like most languages, I would guess, are not always the same. When writing English it is important to be as specific as possible, to clarify, like Harley did in her examples. But you were referring to someone speaking those sentences. I am a native American (not Indian) speaker of English, and when someone says to me, "I am an English teacher", they mean that they teach the English language. Unless they have a thick 'British' accent, then I may wonder exactly what they meant. (they may be saying that they are a teacher from England) Now in England this may be different. So the word which is stressed isn't as important as the context in which it is delivered.