按条件f对关系R进行选择,其关系代数表达式为( )。
参考答案:C
单词拼写。
1.He broke the law and was caught trying to f the country.
2.Each year Americans c a high percentage of the world's energy.
3.They put their arms around each other and h .
4.When I got to the airport,he was already a the plane.
5.Do you know the p for obtaining a new passport?Next year,I will go to Australia.
6.Rice is the (主要的)crop of India.
7.A party of soldiers was landed secretly at night on the enemy coast;
their (使命)was to blow up the radio station.
8. (非官方的)estimates put the figure at over 2 million.
9.The (辨认)of the crash victims was a long and difficult task.
10.They came to a (妥协)over the exact amount to be paid.
在反应器进行联锁复位时,必须确保()。
A.裂解气压缩机能正常出料,减小压缩机排出压力波动
B.反应器出口冷却器投用正常
C.反应器充压平衡
D.高压塔塔顶物料合格