meaning - "I only teach you" vs. "I teach only you" vs. "I teach you only"

• I only teach you.


• I teach only you.


• I teach you only.

I think that all the sentences have same meaning, but my teacher says that they are different from each other.

I think that the expressions are different but their meaning are same.

Can you help me understand the meaning of each sentence?

Answer

Only is one of the words (like even, too, and also) that have a stressed focus word in the sentence.

The focus word takes a heavy contrastive stress in speech, no matter where only occurs.

• She only talked to Mrs. McGrew about Bill. (not talking about anybody else)


• She only talked to Mrs. McGrew about Bill. (not talking to anybody else)


• She only talked to Mrs. McGrew about Bill. (no activity except talking)

In these sentences, only appears before the verb phrase, which contains the focus in each case.

It can also appear right before the focus word (or right after, if the focus is a noun).

• She talked to Mrs. McGrew only about Bill.


• She talked only to Mrs. McGrew about Bill.


• She talked to Mrs. McGrew about Bill only.


• She talked about Bill to Mrs. McGrew only. (this works better at the end of a sentence)

Of course, in writing, there is no stress, so it's harder to tell what the focus is.
So in writing it's safest to put only right before the focus word (the word with contrastive stress)

This rule is discussed here, with references and examples.