题目

阅读理解        阅读下面材料，从每题所给的A、B、C、D四个选项中选出最佳选项。 I am off on a trip on my own. Yes ! Alone! I can't wait to get going to Europe to see     some cities I really want to visit. It is great because I can choose what I want to do in each     city. I am going to travel by train on the Eurorail. The train trip was fast and the views of the countryside were amazing. Now 1 am in  Salzburg, Austria. The quiet hills of Austria are a great place to relax. The movie The       Sound of  Music was filmed around this area如图直线AC与函数y=mx的图象交于A、C两点，A（2，3），C点的纵坐标为-1，O为坐标原点．①求直线AC的解析式和m的值；②求△AOC的面积．