职教组卷基于海量职教高考试题库建立的在线组卷及学习系统
职教组卷
  • 题型:英语知识运用 题类:模拟题 难易度:中档

    They had walked in wrong directions for quite some time ________ they realized that they had got lost.

    A. since    B. while    C. before    D. after
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