(S (S (BASENP (PRP It)) (VP (VP (VBD was) (ADVP (RB initially))) (VP (VP (VBN tested) (PRT (RP out))) (PP (IN on) (NP (BASENP (DT a) (JJ large) (NN subset)) (PP (IN of) (NP (BASENP (DT the) (NNS pages)) (PP (IN of) (NP (BASENP (NNP Wikipedia)) (COMMA ,) (NP (BASENP (DT a) (JJ free) (JJ online) (NN encyclopedia) (NN project)) (SBAR (WHNP (WDT which)) (S (VP (VBZ preserves) (NP (BASENP (DT every) (NN change)) (VP (VBN made) (PP (TO to) (NP (BASENP (DT each)) (PP (IN of) (BASENP (PRPD its) (NNS articles)))))))))))))))))))) (PERIOD .))