题目内容：
设参考答案：
选择题：设是一个半群，α∈S，在S上定义一个二元运算口，使得对于S中的任意元素X和Y，都有X□ y =x*
- 题目分类：计算机科学与技术（第二学期）
- 题目类型：选择题
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He is less careful than his sister.A、正确B、错误
He is less careful than his sister.A、正确B、错误
退出Windows 10 系统时，只要直接关闭电源即可。A、正确B、错误
退出Windows 10 系统时，只要直接关闭电源即可。A、正确B、错误
His father began to work ______ he was seven years
His father began to work ______ he was seven years old.A、as old asB、as early asC
PowerPoint中，选择PowerPoint中的文本时，如果文本选择成功之后，下次就无法再选择该
PowerPoint中，选择PowerPoint中的文本时，如果文本选择成功之后，下次就无法再选择该段文本。A、正确B、错误
The reason _____ he was late for the meeting is __
The reason _____ he was late for the meeting is _____ his car broke down on the