问题解决是由一定情境引起的，需要运用一系列的认知操作来解决某种疑难的过程，它具有以下哪些基本特点？（） 问题情境性。 目的指向性。 操作序列性。 认知操作性。
Mary has a view called EMP_DEPT_LOC_VU that was created based on the EMPLOYEES, DEPARTMENTS, and LOCATIONS tables. She granted SELECT privilege to Scott on this view. Which option enables Scott to eliminate the need to qualify the view with the name MARY .EMP_DEP_LOC_VU each time the view is referenced?（） Scott can create a synonym for the EMP_DEPT_LOC_VU bus using the command: CREATE PRIVATE SYNONYM EDL_VU FOR mary.EMP DEPT_LOC_VU; then he can prefix the columns with this synonymn.。 Scott can create a synonym for the EMP_DEPT_LOC_VU by using the command: CREATE SYNONYM EDL_VU FOR mary.EMP_DEPT_LOC_VU; then he can prefix the columns with this synonym.。 Scott can create a synonym for the EMP_DEPT_LOC_VU by using the command: CREATE LOCAL SYNONYM EDL_VU FOR mary.EMP DEPT_LOC_VU; then he can prefix the columns with this synonym.。 Scott can create a synonym for the EMP_DEPT_LOC_VU by using the command: CREATE SYNONYM EDL_VU ON mary(EMP_DEPT_LOC_VU); then he can prefix the columns with this synonym.。 Scott cannot create a synonym because synonyms can be created only for tables.。 Scott cannot create any synonym for Mary's view. Mary should create a private synonym for the view and grant SELECT privilege on that synonym to Scott.。
常见的调压措施有哪些？
高压配电装置的操作走廊宽度一般规定（） 0.8---1m。 1---1.5m。 1.5---1.8m。
You perform differential incremental level 1 backups of your database on each working day and level 0 backup on Sundays， to tape. Which two statements are true about differential incremental backups（） The backup performed on Sundays contains all the blocks that have ever been used in the database.。 The backup performed on Sundays contains all the blocks that have changed since the last level 1backup. 。 The backup performed on each working day contains all the blocks that have changed since the lastlevel 0 backup.。 The backup performed on Monday contains all the blocks that have changed since the level 0 backup，and every other working day contains all the blocks that have changed since the level 1 backup.。
使用筒刀前，需要检查筒刀的（）是否完好。
