单选题 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

【正确答案】 D

【答案解析】[解析] 各项的意思是：hard to invent难以发明；hard to understand难以理解；hard to imagine难以想象；hard to believe难以相信。划线单词incredible的意思是：难以置信的。句意是：几乎每个星期，技术都会取得一些进步，但在50年前，这似乎是难以置信的。所以，答案是D。