已知抛物线y=a（x﹣m）²+n与y轴交于点A，它的顶点为点B，点A、B关于原点O的对称点分别为C、D．若A、B、C、D中任何三点都不在一直线上，则称四边形ABCD为抛物线的伴随四边形，直线AB为抛物线的伴随直线．

欧洲西部突出的特征是（    ）

①国家众多、人口稠密  ②经济发达  ③语言相同  ④气候炎热

News
Place: playground(操场)
Time: 5:00pm this Thursday
Program(节目): a friendly soccer game between Class 3 and Class 4
Lost
Hello, everyone! Do you see a cat in the park? Its name is Molly. It is a black cat. If you see Molly, please call Mary at 820-9291.
Wanted
Do you play the guitar well? We need a guitar teacher to teach kids between the ages of seven and ten. The work time is from Tuesday to Saturday, 300 yuan for each day. Welcome to join us