My family is ____(计划) a journey to China in the winter. Our first ____(选择) is to visit Beijing, one of the____(大) places in the world.. So we need to ____(预订) the plane tickets. To tell you the truth, we like going by train____ (好) . But we think it is too slow and it ____(花费) much time. Though going by plane is more____(昂贵的)，it goes____(快) and saves time. Some people may think it's not ____(安全) , but our family all____(赞同)it's our favorite way to travel.

澳门的主要经济部门是（　　）

古人云：“橘生淮南则为橘，生于淮北则为枳，叶徒相似，其实味不同。”这里所说的味道不同的主要原因有    (    )

  ①气候不同②种植方法不同  ③品种不同  ④水土不同

如图所示，倾角为30°，重为100N的斜面体静止在粗糙水平面上．一根弹性轻杆一端垂直固定在斜面体上，杆的另一端固定一个重为20N的小球，斜面体和小球处于静止状态时，下列说法正确的是（   ）

位于地势第三阶梯，海拔在50米以下，临黄海和东海的地形区是（  ）。