----Just my luck! The computer broke down again. ----There are so many _____.You can try another one. A. accessible B. reachable C. abundant D. acceptable 答案:A 解析: abundant丰富的;富裕的;acceptable可以接受的;值得接受的。如果25x2-kxy+49y2是一个完全平方式,那么k的值是
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A.1225B.35
C.-70D.±70