He's under stress because he has too much work to do.
A:pain
B:pressure
C:difficulty
胚芽鞘产生生长素的部位、感受单侧光刺激的部位和弯曲生长的部位分别是
①画出与△ABC关于y轴对称的△A1B1C1,求点C1的坐标。
②以原点O为位似中心,在第四象限画一个△A2B2C2,使它与△ABC位似,并且△A2B2C2与△ABC的相似比为2:1.