Trouble Working out these Philosophy Logic Problems??

Using Rules of Inference and Rules of Replacement, we were given some translation problems that we're supposed to write out some proofs for. I've been working on other problems similar to these, but these four are giving me some trouble. I've tried working backwards, but its just not very clear to me right now. If anyone can help me out, it would be great! Thanks!

Problem 1:
Prove: E⊃M
1. (A⊃ (E ⊃~F)
2. H v (~F ⊃ M)
3. A
4. ~H

Problem 2.

Prove: ~P
1. ( L iff N ) ⊃ C
2. (L iff N ) v (P ⊃C)
3. ~E ⊃C
4. ~C

Problem 3.
Prove: A⊃K
1. (B v K) ⊃ (A ⊃G)
2. ( B v E) ⊃ (G⊃K)
3. B · ~H)

Problem 4:
Prove: G
1. (~K·~N) ⊃ [(~P⊃K) · (~R⊃G)]
2. K⊃N
3. ~N · B
4. ~P v ~ R