题目

—By the way，have you moved into the new house?   —Not yet．The walls ________．   A．were painted    B．are being painted    C．are painted     D．are painting 答案：B如图，扇形MON的圆心角为直角，半径为2，正方形OABC内接于扇形，点A、C、B分别在OM、ON、上，过作ME⊥CB交CB的延长线于E，则图中阴影部分的面积为    ．