题目内容：
7单选(2分)The visitors tiptoed to the workroom_________ they should interrupt the painter’s work.
得分/总分
A.
provided
B.
unless
C.
if
D.
lest
参考答案：
选择题：7单选(2分)The visitors tiptoed to the workroom_______
- 题目分类：兰州交通大学大学英语4
- 题目类型：选择题
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The visitors tiptoed to the workroom_________ they should interrupt the painter’s work.
得分/总分
A.
provided
B.
unless
C.
if
D.
lest