( ( ( ( ( Three-sided shapes ) ( are triangles ) ) and ) ( ( four-sided shapes ) ( are quadrilaterals ) ) ) . )
(ROOT (S (S (NP (JJ Three-sided) (NNS shapes)) (VP (VBP are) (NP (NNS triangles)))) (CC and) (S (NP (JJ four-sided) (NNS shapes)) (VP (VBP are) (ADJP (JJ quadrilaterals)))) (. .)))
Three-sided shapes are triangles and four-sided shapes are quadrilaterals.
(ROOT (S (NP (NP (DT The) (CD eight) (NNS sides)) (PP (IN of) (NP (DT an) (NN octahedra)))) (VP (VBP are) (PP (IN in) (NP (NP (DT the) (NN shape)) (PP (IN of) (NP (DT a) (NNS triangles)))))) (. .)))