( ( ( The temperature ) ( of ( ( the water ) ( in ( the ( crater lake ) ) ) ) ) ) ( ( decreased slightly ) . ) )
(ROOT (S (NP (NP (DT The) (NN temperature)) (PP (IN of) (NP (NP (DT the) (NN water)) (PP (IN in) (NP (DT the) (NN crater) (NN lake)))))) (VP (VBD decreased) (ADVP (RB slightly))) (. .)))
The temperature of the water in the crater lake decreased slightly.
(ROOT (S (NP (NNS Craters) (CC and) (NNS rifts)) (VP (VBP become) (NP (NNS lakes)) (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VBP fill) (PP (IN with) (NP (NN water))))))) (. .)))