Whathaspuzzledthescientistsisthataslightchangeinitsenvi...
來源:國語幫 2.99W
問題詳情:
What has puzzled the scientists is that a slight change in its environment ______ have pushed the rare species over the edge into extinction.
A. would B. must C. shall D. should
【回答】
D
知識點:情態動詞
題型:選擇題