我国家庭农业生产规模很小，全国平均每户承包土地（）亩左右。
食品中的植物性毒素主要有哪些？
Given that tables T1 and T2 contain the following rows: Table T1: C1 C2 5 4 5 2 5 5 Table T2: C1 C2 5 1 5 2 5 3 Which of the following queries will return only those rows that exist in T1 and not in T2?（） SELECT * FROM T1 MINUS SELECT * FROM T2。 SELECT * FROM T1 EXCEPT SELECT * FROM T2。 SELECT * FROM T2 UNION EXCEPT SELECT * FROM T1。 SELECT * FROM T1 NOT EXISTS SELECT * FROM T2。
Due to slow response times， a customer purchased additional memory. After the memory was installed，response time was not improved. They complained to the pSeries technical specialist. Which of the following questions should be asked of this customer？（） Who recommended the memory purchase？。 Have more users been added since the memory purchase？。 Why were additional CPUs not ordered at the same time as the memory？。 Did a performance analysis of peak periods show a memory bottleneck？。
在Excel“格式”工具栏中提供了几种对齐方式：（）
某用户希望增加一个备份存储池在现有的DS5000存储系统上，那种磁盘提供了最好的选择：（）
