( ( ( ( ( ( More ( than three ) ) forces ) , ) Gravity ) , ) ( ( ( Electric and ) Magnetic ) . ) )
(ROOT (S (NP (NP (QP (JJR More) (IN than) (CD three)) (NNS forces)) (, ,) (NP (NNP Gravity)) (, ,)) (VP (VP (VBZ Electric)) (CC and) (VP (VBZ Magnetic))) (. .)))
More than three forces, Gravity, Electric and Magnetic.
(ROOT (S (NP (NNP Gravity) (CC and) (NNP magnetism)) (VP (VBP are) (NP (DT both) (JJ common) (NNS forces))) (. .)))
Gravity and magnetism are both common forces.