问题补充：
The students were so when they heard the news.
A. frustrating, frustrated
B. frustrated, frustrating
C. frustrated, frustrated
D. frustrating, frustrating
答案：
A. frustrating, frustrated
(答案→)B. frustrated, frustrating
C. frustrated, frustrated
D. frustrating, frustrating
解析：frustrating是用来修饰物体的，而frustrated是修饰人的，故选答案为B
