Explain why Mary Warren thinks Elizabeth should speak civily to her in The Crucible?

In Act II, Mary Warren does not like the way that
Elizabeth Proctor is speaking to her.  She feels that she deserves more respect now that
she is connected to the court that is investigating the allegations of
witchcraft.

Before this, Mary has simply been a servant
working for Elizabeth Proctor.  As such, there is no reason that Elizabeth has to be
particularly respectful to her (especially in those days).  But now Mary is connected to
the court and she feels that she is more important and deserves
respect.

Because of this power, Mary sort of threatens
Elizabeth as well.  She points out that Elizabeth has been accused but that Mary's
testimony saved her.  This implies that if she makes Mary mad, Mary turn against
her.