( Beta-particles ( ( are ( emitted ( in ( ( a spectrum ) ( of energies ) ) ) ) ) ; ) )
(ROOT (S (NP (NNS Beta-particles)) (VP (VBP are) (VP (VBN emitted) (PP (IN in) (NP (NP (DT a) (NN spectrum)) (PP (IN of) (NP (NNS energies))))))) (: ;)))
Beta-particles are emitted in a spectrum of energies;
(ROOT (S (NP (NN Beta) (NN decay)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (DT an) (JJ unstable) (NN nucleus)) (VP (VBZ emits) (NP (NP (DT a) (JJ beta) (NN particle)) (CC and) (NP (NN energy))))))) (. .)))