第13题: [单项选择]A. Janet is preparing for her exams. B. Janet is a hardworking student. C. Janet has spent too much time working on her papers. D. Janet is a student. 参考答案:A 答案解析:[听力原文] Janet has to spend so much time in the library to finish her papers before the exams b
第19题: [单项选择]下列叙述中不是计算机病毒的特征是( )。 A. 局部性 B. 传染性 C. 隐蔽性 D. 破坏性 参考答案:A 答案解析:[解析] 计算机病毒是一种特殊的具有破坏性的计算机程序,它具有自我复制能力,可通过非授权入侵而隐藏在可执行程序或数据文件中。当计算机运行时源病毒能把自身精确拷贝或者有修改地拷贝到程序体内,影响和破坏正