( or ( , ( it ( ( might ( ( ( be ( ( a little ) ( too tight ) ) ) , ) ( so ( it ( knocks ( when ( it ( ( ( expands and ) contracts ) ( from ( ( heat and ) cold ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (CC or) (, ,) (NP (PRP it)) (VP (MD might) (VP (VB be) (ADJP (NP (DT a) (RB little)) (RB too) (JJ tight)) (, ,) (SBAR (IN so) (S (NP (PRP it)) (VP (VBZ knocks) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBZ expands) (CC and) (VBZ contracts) (PP (IN from) (NP (NN heat) (CC and) (NN cold))))))))))) (. .)))
or, it might be a little too tight, so it knocks when it expands and contracts from heat and cold.
(ROOT (S (NP (NP (DT The) (NN liquid)) (PP (IN in) (NP (DT a) (NN thermometer)))) (VP (VP (VBZ expands)) (CC or) (VP (VBZ contracts) (S (VP (TO to) (VP (VB respond) (PP (TO to) (NP (NN heat) (CC or) (NN cold)))))))) (. .)))