问题补充:
With the help of high technology, many new substances(物质)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:考查时态语态:时间是in the past years.时态用现在完成时,new substances和discover是被动关系,句意是:随着高科技的发展,在过去的这些年里,很多新的物质被发现了。选D。