题目

With the help of high technology, more andmore new substances ___in the past few years.A. discoveredB. have discoveredC. had been discoveredD. have been discovered

With the help of high technology, more and more new substances ___in the past few years.

A. discovered

B. have discovered

C. had been discovered

D. have been discovered

题目解答

答案

D. have been discovered

解析

本题考查现在完成时的被动语态的用法。解题关键点在于：

  1. 时间状语"in the past few years"提示使用现在完成时；
  2. 主语"substances"与动词"discover"之间是被动关系，需用被动语态；
  3. 现在完成时的被动结构为have/has been done。

选项分析

  • A. discovered：缺少"have been"，无法构成被动语态；
  • B. have discovered：主动语态，不符合题意；
  • C. had been discovered：过去完成时，时间状语应为更早的时间点；
  • D. have been discovered：正确匹配现在完成时的被动语态。