問題詳情

【題組】23. Unluckily, humans have long ____ planting only one staple crop in an area.
(A) being used to
(B) used to
(C) been used to
(D) been used as

參考答案

答案：B[無官方正解]
難度：適中0.5
統計：A(0),B(5),C(2),D(0),E(0)