阿摩線上測驗
17. For a long time, scientists have trouble explaining how young children can learn the grammatical rules and
sounds _______ to communicate in words.
(A) require
(B) requiring
(C) required
(D) requires
答案：登入後查看
統計： A(15), B(45), C(169), D(8), E(0) #902844
統計： A(15), B(45), C(169), D(8), E(0) #902844
