A:①②③
B:②③④
C:①②④
D:①③④
如图是用双缝干涉测光的波长的实验设备示意图.
a图中①是光源,⑤是光屏,它们之间的②、③、④依次是滤光片、____和____.(选填单缝、双缝、)
b以下哪些操作能够增大光屏上相邻两条亮纹之间的距离____.
A.增大③和④之间的距离
B.增大④和⑤之间的距离
C.将红色滤光片改为绿色滤光片
D.增大双缝之间的距离.
Hello, I'm Tom. I'm ____ and ____. I do exercise every morning. I run for 30 ____. I ____ eat vegetables and fruit. I don't eat too much meat. Because it's ____ for me. I work hard at school and at sports. Sometimes I help my parents at home.