阿摩線上測驗
46. What does “this” in the third paragraph refer to?
(A) Recording messages.
(B) Conducting research.
(C) Behavior learning.
(D) Whistle copying.
答案：登入後查看
統計： A(6), B(19), C(14), D(60), E(0) #866854
統計： A(6), B(19), C(14), D(60), E(0) #866854
