某施工单位承担一土石坝施工任务，该单位对坝基开挖做了施工组织设计，坝基基坑深为5.2m，采用药壶爆破法施工，土方量为9000m3，平均运距为10km，合同工期为8天。该施工单位有甲、乙、丙液压挖掘机各4台、2台、2台，A、B、C自卸汽车各12台、30台、18台，挖掘机的机械利用率为0.9，自卸汽车的机械利用率为0.95，其主要参数见表1、表2。
若挖掘机和自卸汽车只能取一种，而数量没有限制，如何组合最经济？说明理由。并计算其单方挖运直接费。
Which of the following calendaring syntax expressions would evaluate to the last day of every month？（） FREQ = MONTHLY； BYMONTHDAY = 31。 FREQ = MONTHLY； BYMONTHDAY = -1。 FREQ = DAILY； BYDAY = -1。 FREQ = MONTHLY； BYDAY = 31。 FREQ = DAILY； BYMONTHDAY = LAST_DAY。
You issued the following statement in your SQL*Plus session： SQL>ALTER SESSION ENABLE RESUMABLE TIMEOUT 600； Which operation is neither suspended nor resumed using the Automatic Resumable Allocation feature in your database？（） creating a table in your schema and you exceed your allocated space quota on the tablespace。 executing a long query that involves a sort operation and the statement runs out of temporary space。 loading data into tables by using the SQL*Loader and the number of extents in the table reaches the maximum limit。 creating a table in a dictionary-managed tablespace with an explicit MAXEXTENTS setting which results in an out of space error。
在间隙距离不变的条件下，均匀电场的击穿电压（）不均匀电场的击穿电压。 大于。 等于。 小于。
You want to estimate the size of a table by using the Oracle Enterprise Manager. On which data is the size of the table NOT based？（） column sizes。 column data types。 PCTFREE。 projected number of row。 PCTUSED。
You are attempting to secure a MySQL server by using SSL encryption.
On starting MySQL, you get this error:
130123 10:38:02 [ERROR] mysqld: unknown option '—ssl'
What is the cause of the error?（）
