問題詳情

24. The reason why the salmon swims from the ocean back to the river of its birth remains __________.
(A) not known
(B) not to known
(C) unknowing
(D) unknown

參考答案

答案：[無官方正解]
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)