問題詳情

36. With the help of high technology, more and more new substances ______ in the past years.
(A) discovered
(B) have discovered  
(C) had been discovered
(D) have been discovered

參考答案

答案:D
難度:適中0.5
統計:A(0),B(0),C(0),D(0),E(0)

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