如图，南北向的公路上有一点A，东西向的公路上有一点B，若要在南北向的公路上确定点P，使得△PAB是等腰三角形，则这样的点P最多能确定____ 个．

读美国示意图，图中②地区人口密集，城市集中，适宜发展（　　）

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       Both the British and Americans speak English. However, there are several differences between American English and British English. For example, the words they use in daily life are not the same. The British call the first floor of a building the ground floor. The floor above the ground floor is the first floor, which Americans call the second floor. Once you go to Britain and America, you may notice other differences. The British usually hide their feelings. They don't often start a talk with strangers. On the train the British often spend their time reading newspapers or books. But Americans are more active and easier to talk with.