My homework: Design a Full-Adder using NAND-2 only. Design a Full-Adder using NOR-2 only.

First, I assembled the definition circuit of Full-Adder (the 3rd circuit).

Second, I change the above circuit into a circuit using only basic gates (NOT, AND, OR) (the 4th). I also assembled a Full-Adder with the XOR gates as (A+B).(A'+B') (the 5th circuit).

Then I change it into a NAND-2 only circuit (the 2nd). I used Wikipedia's NAND-2-only XOR circuit and hints to reduce 2 NAND gates at the AND gate route on the 3rd circuit. 

Lastly, I create a NOR-2-only variation (the 1st).