题目

There are so many foggy days recently, we all wonder_________. A. how is the air polluted B. why the air is seriously polluted C. what can we do to prevent that bad weather D. what are the real reasons 答案：B已知：如图，在正方形ABCD中，F是AD的中点，BF与AC交于点G，则△BFC与四边形CGFD的面积之比是    ．