A．When he can't get his point across. B．When people are not receptive to new ideas. C．when he comes into conflict with his colleagues. D．When it is impossible to learn or to grow in his field.
A.When B. B．When C. C．when D. D．When E.
【参考答案】
B 解析：[听力原文] When does the man feel frustrated? 通......