( ( Sunspot activity ) ( ( follows ( an ( 11-year cycle ) ) ) . ) )
(ROOT (S (NP (JJ Sunspot) (NN activity)) (VP (VBZ follows) (NP (DT an) (JJ 11-year) (NN cycle))) (. .)))
Sunspot activity follows an 11-year cycle.
(ROOT (S (NP (NNS Sunspots)) (VP (VBP occur) (PP (IN in) (NP (DT a) (CD 11) (NN year) (NN cycle)))) (. .)))