题目

第二节：完形填空（共20小题，每小题1.5分，满分30分） 阅读下面短文，从短文后各题所给的四个选项（A、B、C和D）中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。 Man-made Causes Man-made causes probably do the most damage. There are many man-made causes.  21  is one of the biggest man-made problems. Pollution  22  in many shapes and sizes. Burning fossil fuels is one thing that causes pollution. Fossil(化石) fuels(燃料)are fuels made of organic matter such as coal, or oil. when fossil fuels are burned they 在△ABC中，已知（a+b+c）（a+b-c）=ab，则∠C的大小为______．