_______ the Internet is of great help, I don't think it's a good idea to spend too much time on it.
A.IfB.WhileC.BecauseD.As在线课程B
解析：考查连词。此处意思是“尽管网络很有帮助，……”，选项中能表示让步的只有while，相当于although。其他选项都不能表示让步的意思。