問題詳情

35.We must be ______________guard against our competitor's new market release.
(A) in
(B)on
(C) at
(D)with

參考答案

答案：B
難度：困難0.394587
統計：A(157),B(277),C(59),D(98),E(0)

用户評論

【gbhjkl2】評論

on guard against 警惕

【Alina】評論

???

【smiley】評論

on guard=on duty值班