This ____ my friend.
Some children prefer to eat junk food ________ it's not good for their health.
如果一个水平放置的图形的斜二测直观图是一个底面为45°,腰和上底均为1的等腰梯形,那么原平面图形的面积是( )
如图,已知△ABC.求作BC边上的高.(要求用尺规作图,不写作法,保留作图痕迹)