玻璃幕墙既可以反射光线，又可以折射光线．如图是小明同学周一在操场上升旗时看到教室的玻璃幕墙上的红旗的像，它是由光的______形成的______（填“实”或“虚”）像．

There is ____in  this lesson.   [ ]

A. something difficult  

B. difficult something   

C. anything difficult  

D. difficult anything