Comment on the dramatic irony in each scene: The omens of tragedy even in the romantic language of act 2 scene 2.I do not understand this question,...

From the question asked, it seems that your teacher is looking for examples of foreshadowing in the text.  An omen of tragedy would be anything that the characters say that foreshadows the tragic end of the play of which they are unaware.  Some examples from Act 2 Scene 2 would include:

When Romeo says:

"I have night's cloak to hide me from their sight;
And but thou love me, let them find me here:
My life were better ended by their hate,
Than death prorogued, wanting of thy love."

Stating that Juliet's kinsmen would kill him if was found but that he would rather be killed as a result of their hate than want for her love.

When Juliet says:

"Sweet, so would I:
Yet I should kill thee with much cherishing.
Good night, good night! parting is such sweet sorrow,
That I shall say good night till it be morrow."

Here she is stating that she would keep Romeo close but with that desire would kill him.

So, as you are reading, you are looking for times when the characters foreshadow what happens at the end.  I hope this helps!