题目内容：
78. Peter was about to unlock the door _______ he found someone had broken into the room.A. once C. than
B. before D. when
参考答案：
选择题：78. Peter was about to unlock the door _______ he
- 题目分类：新疆师范大学2021级学生第一学期结业课程考试《大
- 题目类型：选择题
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A. once C. than
B. before D. when