A：(x-y) =(y-x)
B：(x-y) =-(y-x)
C：(x+y)(y-x)=(x+y)(x-y)
D：(x+y) =(-x-y)
为此，我校九（2）班思想品德学习兴趣小组开展了“宣传五中全会精神，关心祖国未来发展”为主题的系列探究活动。请你也参与其中并完成下列任务。
He won in the story competition and his parents were very .
