問題詳情

17. For a long time, scientists have trouble explaining how young children can learn the grammatical rules andsounds _______ to communicate in words.
(A) require
(B) requiring
(C) required
(D) requires

參考答案

答案:C
難度:困難0.352941
統計:A(1),B(5),C(6),D(2),E(0)

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