Johnny's Surprise<br>Yesterday was Johnny's birthday. His parents decided to throw him a party. All of his little friends came. They ate cake and ice cream and played games. As he opened his gifts, his parents surprised him with a new bike.
Johnny and his friends ate cake and ice cream and played games after he opened his gifts.
The context implies that Johnny and his friends did these things before, not after, opening his presents.  However, there's nothing precluding them from continuing these activities after the gift opening as well.  Once again, my alteration was subtle enough to go undetected by the system.
( z1 and :op ( z2 eat :ARG0 ( z3 and :op ( z4 person :name ( z5 name :op "Johnny" ) ) :op ( z6 person :ARG0-of ( z7 have-rel-role :ARG1 z4 :ARG2 ( z8 friend ) ) ) ) :ARG1 ( z9 and :op ( z10 cake ) :op ( z11 ice-cream ) ) ) :op ( z12 play :ARG0 z3 :ARG1 ( z13 game ) ) :time ( z14 after :op ( z15 open :ARG0 z4 :ARG1 ( z16 gift :poss z4 ) ) ) )