At first, children find it difficult to distinguish words and other mental symbols from the objects and actions to which they refer.
( ( At first ) ( , ( children ( ( find ( it ( difficult ( to ( ( distinguish ( ( words and ) ( other ( mental symbols ) ) ) ) ( from ( ( the ( ( objects and ) actions ) ) ( ( to which ) ( they refer ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (JJ first))) (, ,) (NP (NNS children)) (VP (VBP find) (S (NP (PRP it)) (ADJP (JJ difficult) (S (VP (TO to) (VP (VB distinguish) (NP (NP (NNS words)) (CC and) (NP (JJ other) (JJ mental) (NNS symbols))) (PP (IN from) (NP (NP (DT the) (NNS objects) (CC and) (NNS actions)) (SBAR (WHPP (TO to) (WHNP (WDT which))) (S (NP (PRP they)) (VP (VBP refer)))))))))))) (. .)))
Children cannot always easily distinguish words and other mental symbols from objects and actions.
( Children ( ( ( ( can not ) ( always easily ) ) ( ( distinguish ( ( words and ) ( other ( mental symbols ) ) ) ) ( from ( ( objects and ) actions ) ) ) ) . ) )
(ROOT (S (NP (NNP Children)) (VP (MD can) (RB not) (ADVP (RB always) (RB easily)) (VP (VB distinguish) (NP (NP (NNS words)) (CC and) (NP (JJ other) (JJ mental) (NNS symbols))) (PP (IN from) (NP (NNS objects) (CC and) (NNS actions))))) (. .)))