从方框中选择合适的句子补全对话。有两个多余的选项。
A：Where have you been, Mike? I called you, but you weren't in.
B：_______
A：Why did you go there?
B：_______ It has made the old who live nearby sick.
A：_______
B：Do you think “Greener China” can do something?
A：_______ I think we should write a letter to the program about the pollution.
B：_______It's our duty to protect the environment.

I've been to a farm.     B．Good idea! C．I've been to a rubber factory. D．Because I found the factory pouring waste water into the river. E．That's terrible.     F．What should we do to stop it? G．Yes , of course.