东南亚的印度尼西亚多火山、地震的原因是( )
A:处在板块内部
B:处在板块交界处
C:位于印度洋中心
D:位于亚洲内陆
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如图,B是AC的中点,BE→=2OB→,P是平行四边形BCDE内(含边界)的一点,且OP→=XOA→+yOB→x,y∈R.有以下结论:
①当x=0时,y∈2,3;
②当P是线段CE的中点时,x=-12,y=52;
③若x+y为定值1,则在平面直角坐标系中,点P的轨迹是一条线段;
④x﹣y的最大值为﹣1;
其中你认为正确的所有结论的序号为
____ .
衣着素净( )