题目内容：
24. The two scholars worked at the task of writing a preface to the new dictionary for three hours ____ last night.
(A) at length
(B) in full
(C) on end
(D) in time
参考答案：
选择题：24.The two scholars worked at the task of writing
- 题目分类：郑州工程技术学院-大学英语（2）.
- 题目类型：选择题
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The two scholars worked at the task of writing a preface to the new dictionary for three hours ____ last night.
(A) at length
(B) in full
(C) on end
(D) in time