【简答题】设一个关系A具有a1个属性和a2个元组,关系B具有b1个属性和b2个元组,则关系AxB具有______个属性和______个元组。
【判断题】波峰焊中如果肋焊剂喷涂量过多容易造成焊点不全。
【单选题】三餐的能量分配合理的比例是 A . C. B.4:3:3 C. D. E.3:3:4
【单选题】It has not been decided who will ______ to the post of chairman of the board, the former holder of which succeeded ______the company world famous. [ ]
【单选题】设一个关系A具有a1个属性和a2个元组,关系B具有b1个属性和b2个元组,则关系A×B具有 ()个属性
【单选题】在oxy平面内运动的一质点,其运动方程为 r =5cos5t i + 5sin5t j ,则其速度大小与法向加速度分别为
【单选题】设一个关系A具有a1个属性和a2个元组,关系B具有b1个属性和b2个元组,则关系AB具有()个元组。
【简答题】非谓语动词翻译练习: 1.I would appreciate your providing me with an estimate of both time and costs in order for you to prepare an appraisal that will meet the lender’s requirements. 2. The owner retains the ri...