问题
选择题
With the help of high technology, more and more new substances ______ in the past 10 years.
A．discovered
B．have discovered
C．had been discovered
D．have been discovered
答案
答案：D
考查时态。in the past+时间段，后用现在完成时态。句意：在先进技术的帮助下，在这十年间越来越多的新物质被发现。故选D。