设SC(学号,课号,成绩)为选课关系,则下面的元组表达式{t|(u)(SC(u)Λ(u[2]=‘C2’Ⅴu[2]=‘C4’)Λt[1]=u[1])}的中文含义是什么?
检索选修课程号为C2或C4课程的学生学号。
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Choose the closest paraphrased version after the following sentence or the italicized part.
Kaz Tanaka had wakened in a frightening new world—a world whose dominant sound was a silence broken only by the cries of the dying.()
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