Question

4. Which characters exchange these lines—and in what order—in Act I, Scene 1 of A Midsummer Night's Dream?    I frown up him, yet he loves me still.    O that your frowns would teach my smiles such skill!

Answer 1

These lines are quoted from Shakespeare's "A Midsummer Night's Dream."
The two characters that are exchanging this dialogue are Hermia and Helena.

Your answer is: Hermia, Helena 

Have an amazing day mate!