( ( ( ( ( Light ( usually ( travels ( in ( a ( straight ( line path ) ) ) ) ) ) ) , ) but ) ( it ( can ( be ( scattered ( by ( particles ( such ( as ( ( the ( nitrogen molecules ) ) ( in ( ( the ( Earth 's ) ) atmosphere ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (NNP Light)) (ADVP (RB usually)) (VP (VBZ travels) (PP (IN in) (NP (DT a) (JJ straight) (NN line) (NN path))))) (, ,) (CC but) (S (NP (PRP it)) (VP (MD can) (VP (VB be) (VP (VBN scattered) (PP (IN by) (NP (NP (NNS particles)) (PP (JJ such) (IN as) (NP (NP (DT the) (NN nitrogen) (NNS molecules)) (PP (IN in) (NP (NP (DT the) (NN Earth) (POS 's)) (NN atmosphere))))))))))) (. .)))
Light usually travels in a straight line path, but it can be scattered by particles such as the nitrogen molecules in the Earth's atmosphere.
(ROOT (S (NP (NNP Light)) (VP (VBZ is) (VP (VBN scattered) (PP (IN from) (NP (NP (NNS molecules)) (PP (IN in) (NP (PRP$ our) (NN atmosphere))))))) (. .)))