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题目内容
（郑州航空工业管理学院-大学英语）
To tell you the truth, it.s very hard for us to help them get rid of Internet addiction. But we _________ on this problem trying to improve the situation.
（4.0分）
4.0 分
A、
had worked
B、
are working
C、
had been working
D、
worked
（4.0分）
4.0 分
A、
had worked
B、
are working
C、
had been working
D、
worked
参考答案
