【题目】With the help of high technology, more and more new substances ___in the past few years.
A. discoveredB. have discovered
C. had been discoveredD. have been discovered
在线课程【答案】D
【解析】
考查时态语态。句意：因为有高科技的帮助，在最近几年中，越来越多的新物质已经被发现了。根据时间状语in the past few years,说明使用现在完成时。根据句意新物质和发明之间用被动形式。故D正确。