如图，在△ABC中，AB=AC=BC=2，则 $\overrightarrow{AB}\cdot \overrightarrow{BC}$ =（  ）

阅读下列材料并回答问题

材料一：  中国割香港岛给英国；赔款2100万银元；开放广州、厦门、福州、宁波、上海为通商口岸；英商进出口货物缴纳的税款，中国需同英国商定。

材料二：  中国割让辽东半岛，澎湖列岛，台湾给日本；清政府赔给日本军费2亿白银；清政府开放沙市，重庆，苏州，杭州为通商口岸；允许日本在通商口岸开设工厂。

材料三：  清政府赔款白银4.5亿两；划北京东交民巷为“使馆界”，允许各国驻兵保护，不准中国人居住；清政府保证严禁人民反帝活动；拆毁大沽炮台，允许帝国主义国家派兵驻扎北京到山海关铁路沿线重要地区。

我们中学生要在集体中具有更高的人气指数，就必须（　）

​任务型阅读

    John had a busy weekend. On Saturday morning, he went to the library and studied math. On Saturday afternoon, he went to the park. He played tennis with his friend. Lisa was busy on Saturday, too. She cleaned her room in the morning. In the afternoon, she wrote a letter to her cousin(表妹).

    On Sunday morning, John and Lisa read books at home. On Sunday afternoon, they practiced English. In the evening, they saw an interesting talk show with their parents. They had great fun.