( Drought ( ( can ( be ( defined ( as ( ( an ( ( unusually long ) period ) ) ( without rain ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Drought)) (VP (MD can) (VP (VB be) (VP (VBN defined) (PP (IN as) (NP (NP (DT an) (ADJP (RB unusually) (JJ long)) (NN period)) (PP (IN without) (NP (NN rain)))))))) (. .)))
Drought can be defined as an unusually long period without rain.
(ROOT (S (NP (NNS Droughts)) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (EX there)) (VP (VBZ is) (ADJP (JJ little) (PP (TO to) (NP (NP (DT no) (NN rain)) (PP (IN in) (NP (NP (DT a) (NN period)) (PP (IN of) (NP (NN time)))))))))))) (. .)))