题目

According to a new study， teens focus on rewards and have a hard time learning to avoid punishment or consider the consequences of alternative actions.University College London researchers compared how teens and adults learn to make choices based on the available information. They tracked the way in which 18 volunteers aged 12-17 and 20 volunteers aged 18-32 completed tasks in which they had to choose between abstract symbols.Each symbol was consistently associated with a fixed chance of a reward, punishment, or no outcome. As the trial progressed ， participants learned which symbols were （1）已知∠α与∠β，求作∠AOB=2∠α-∠β．（2）如图，E是正方形ABCD中CD边上任意一点，以点A为中心，把△ADE顺时针旋转90°，画出旋转后的图形．