第3题: [单项选择]按密钥的使用个数,密码系统可以分为______。 A. 置换密码系统和易位密码系统 B. 分组密码系统和序列密码系统 C. 对称密码系统和非对称密码系统 D. 密码学系统和密码分析学系统 参考答案:C 答案解析:[知识点] 加密与认证技术 [评析] 密码系统通常从3个独立的方面进行分类: 1、按将明文转换成密文的操作类型可分为:置换密码和易位密码。 2、按明文的处理方法可分为:分组密
第32题:[单选题] What is a cofferdam ________. A.Tube fitted to an ullage hole B.Area the product is loaded into C.Void or empty space separating two tanks D.Opening in the deck used for cleaning a tank 参考答案:C 【参考译文】空隔舱是隔开两个液舱的小空间。 【解 析】cofferdam 空隔舱
第35题: [单项选择]For what purpose did the speaker go to McCarley’s Bookstore one day A. To find a job. B. To talk to the owner. C. To meet a customer. D. To get a book. 参考答案:D 答案解析:[听力原文]21-25
I was 15 when I walked into MeCarley’s Bookstore in Ashland, Oregon, and began scann