And sometime during the third year, they can imagine objects and events with little or no support from the real world, as when they say to a play partner,  I'm calling Susie on the phone! 
( ( And ( sometime ( ( during ( the ( third year ) ) ) ( , ( they ( can ( ( ( imagine ( ( objects and ) events ) ) ( with ( ( little or ) ( no support ) ) ) ) ( from ( the ( real world ) ) ) ) ) ) ) ) ) ) ( , ( ( as ( ( when ( they ( say ( to ( a ( play partner ) ) ) ) ) ) ( , ( I ( 'm ( calling ( Susie ( on ( the phone ) ) ) ) ) ) ) ) ) ! ) ) )
(ROOT (FRAG (S (CC And) (ADVP (RB sometime)) (PP (IN during) (NP (DT the) (JJ third) (NN year))) (, ,) (NP (PRP they)) (VP (MD can) (VP (VB imagine) (NP (NNS objects) (CC and) (NNS events)) (PP (IN with) (NP (NP (RB little)) (CC or) (NP (DT no) (NN support)))) (PP (IN from) (NP (DT the) (JJ real) (NN world)))))) (, ,) (SBAR (IN as) (S (SBAR (WHADVP (WRB when)) (S (NP (PRP they)) (VP (VBP say) (PP (TO to) (NP (DT a) (NN play) (NN partner)))))) (, ,) (NP (PRP I)) (VP (VBP 'm) (VP (VBG calling) (NP (NP (NNP Susie)) (PP (IN on) (NP (DT the) (NN phone)))))))) (. !)))
Imagining objects and events without support from the real world is challenging for a young child.
( ( ( ( Imagining ( ( objects and ) events ) ) ( without support ) ) ( from ( the ( real world ) ) ) ) ( ( is ( challenging ( for ( a ( young child ) ) ) ) ) . ) )
(ROOT (S (S (VP (VBG Imagining) (NP (NNS objects) (CC and) (NNS events)) (PP (IN without) (NP (NN support))) (PP (IN from) (NP (DT the) (JJ real) (NN world))))) (VP (VBZ is) (VP (VBG challenging) (PP (IN for) (NP (DT a) (JJ young) (NN child))))) (. .)))