【简答题】If you want to get a driver’s license , you will have to apply at a driver’s license office. There you will be required to take a written test for driving in that area. You will also need to pass an e...
【单选题】设关系 R 、 S如下图所示, R ÷ S 的结果为: R a 1 b 1 c 2 a 2 b 3 c 7 a 3 b 4 c 6 a 1 b 2 c 3 a 4 b 6 c 6 a 2 b 2 c 3 a 2 b 2 c 3 a 1 b 2 c 1 S b 1 c 2 d 1 b 2 c 1 d 1 b 2 c 3 d 2