第4题: [单项选择]Hardly a week goes by without some advance in technology that would have seemed incredible. 50 years ago. A. hard to invent B. hard to understand C. hard to imagine D. hard to believe 参考答案:D 答案解析:hard to invent“难以发明的”;hard to understand“难以理解的”;hard to imagine“难以想象的”;incredible“难以置信的”,所以选择“hard t