( ( FREQUENCY ( OF ( TORNADOES Tornadoes ) ) ) ( ( can ( occur ( at ( ( any time ) ( of ( the year ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNP FREQUENCY)) (PP (IN OF) (NP (NNP TORNADOES) (NNPS Tornadoes)))) (VP (MD can) (VP (VB occur) (PP (IN at) (NP (NP (DT any) (NN time)) (PP (IN of) (NP (DT the) (NN year))))))) (. .)))
FREQUENCY OF TORNADOES Tornadoes can occur at any time of the year.
(ROOT (S (NP (NNS Tornadoes)) (VP (MD can) (VP (VB occur) (PP (IN in) (NP (DT any))))) (. .)))