问题补充:
With the help of high technology, more and more substances in the past years.
A. discovered
B. have discovered
C. had been discovered
D. have been discovered
答案:
A. discovered
B. have discovered
C. had been discovered
(答案→)D. have been discovered
解析:考查时态和语态。本题的关键是时间状语in the past years,该时间状语通常与现在完成时连用。既要:在高科技的帮助之下,在过去几年里越来越多的物质被发现了。根据惊句意说明使用被动语态的形式。故D正确。