( ( One example ) ( ( is ( when ( ( a ( boil ( water alert ) ) ) occurs ) ) ) . ) )
(ROOT (S (NP (CD One) (NN example)) (VP (VBZ is) (SBAR (WHADVP (WRB when)) (S (NP (DT a) (NN boil) (NN water) (NN alert)) (VP (VBZ occurs))))) (. .)))
One example is when a boil water alert occurs.
(ROOT (S (NP (NP (CD One) (NN example)) (PP (IN of) (NP (NN matter)))) (VP (VBZ is) (NP (NN water))) (. .)))
One example of matter is water.