A:①②③④
B:①②③
C:①②④
D:①②
如图1是在水槽中看到的水波的____现象;图2是用激光束照射一个不透明的小圆盘时,在像屏上观察到的图样,这是光的____现象.
I don't understand the text there are few new words in it.