教材审核常用的基本方法有()。
A.专家评审法
B.头脑风暴法
C.科学论证法
D.教学实践反馈法
参考答案:A, C, D, E
With nothing on, the Emperor walked in the parade, thinking he _____ the most beautiful clothes in the world. [ ]
A. was dressed himself
B. dressed
C. was dressed in
D. was dressed
如图所示,一束截面为圆形(半径R=1m)的平行紫光垂直射向一半径也为R的玻璃半球的平面,经折射后在屏幕S上形成一个圆形亮区。屏幕S至球心距离为D=(+1)m,不考虑光的干涉和衍射,试问:
(1)若玻璃半球对紫色光的折射率为,请你求出圆形亮区的半径。
(2)若将题干中紫光改为白光,在屏幕S上形成的圆形亮区的边缘是什么颜色?