問題詳情

19.Not until Kentucky’s Mammoth Cave had been^completely explored in 1972 _____.
(A)when was its full extent realized
(B)was its full extent realized
(C)that its full extent was realized
(D)the realization of its full extent

參考答案

答案:B
難度:簡單0.714286
統計:A(0),B(5),C(2),D(0),E(0)

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