As early as 1 1/2 to 2 years, children begin to talk about the past, guided by adults who prompt them and expand on their fragmented recollections.
( ( As ( early ( ( as ( ( 1 1/2 to ) 2 ) ) years ) ) ) ( , ( children ( ( begin ( to ( talk ( about ( ( ( the past ) , ) ( guided ( by ( adults ( who ( ( ( prompt them ) and ) ( expand ( on ( their ( fragmented recollections ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (JJ early) (QP (RB as) (CD 1 1/2) (TO to) (CD 2)) (NNS years))) (, ,) (NP (NNS children)) (VP (VBP begin) (S (VP (TO to) (VP (VB talk) (PP (IN about) (NP (NP (DT the) (NN past)) (, ,) (VP (VBN guided) (PP (IN by) (NP (NP (NNS adults)) (SBAR (WHNP (WP who)) (S (VP (VP (VB prompt) (NP (PRP them))) (CC and) (VP (VB expand) (PP (IN on) (NP (PRP$ their) (ADJP (JJ fragmented)) (NNS recollections)))))))))))))))) (. .)))
Even when prompted by adults who are guiding them, children will never talk about the past. 
( ( ( Even when ) ( prompted ( by ( adults ( who ( are ( guiding them ) ) ) ) ) ) ) ( , ( children ( ( ( will never ) ( talk ( about ( the past ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (RB Even) (WRB when)) (S (VP (VBD prompted) (PP (IN by) (NP (NP (NNS adults)) (SBAR (WHNP (WP who)) (S (VP (VBP are) (VP (VBG guiding) (NP (PRP them))))))))))) (, ,) (NP (NNS children)) (VP (MD will) (ADVP (RB never)) (VP (VB talk) (PP (IN about) (NP (DT the) (NN past))))) (. .)))