(S (S (BASENP (DT The) (NNP Guardian)) (VP (VBZ reports) (SBAR (IN that) (S (NP (BASENP (DT the) (NN strike)) (PRN (COMMA ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (VP (VBN expected) (S (VP (TO to) (VP (VP (VB take) (BASENP (NN place))) (PP (IN on) (BASENP (NNP Thursday)))))))))) (COMMA ,))) (VP (MD will) (VP (VB be) (NP (NP (DT the) (NP (ADJP (JJ first)) (NP (ADJP (JJ national)) (NP (BASENP (NNS teachers) (POS ')) (NN strike))))) (PP (IN in) (BASENP (NN 21) (NNS years)))))))))) (PERIOD .))