假设磁盘每磁道有18个扇区，系统刚完成了10号柱面的操作，当前移动臂在13号柱面上，进程的请求序列如表3.3所示。若系统采用SCAN（扫描）调度算法，则系统响应序列为（1）；若系统采用CSCAN（单向扫描）调度算法，则系统响应序列为（2）。空白（1）处应选择（）。
A、⑦⑩①②④③⑨⑧⑤⑥
B、①⑦⑩②③④⑥⑤⑧⑨
C、⑦⑩①②④③⑥⑤⑧⑨
D、①⑦⑩②③④⑧⑨⑥⑤
Which two statements about subqueries are true? （）
AA subquery should retrieve only one row.
BA subquery can retrieve zero or more rows.
CA subquery can be used only in SQL query statements.
DSubqueries CANNOT be nested by more than two levels.
EA subquery CANNOT be used in an SQL query statement that uses group functions.
FWhen a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.
To determine the space allocated for temporary segments, the DBA can access which of the following views? （）
A、DBA_TABLESPACES
B、DBA_TABLES
C、DBA_SEGMENTS
D、DBA_FREE_SPACE
Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables: EMPLOYEES EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE NEW_EMPLOYEES EMPLOYEE_ID NUMBER Primary Key NAME VARCHAR2(60) Which DELETE statement is valid?（）
A、DELETE FROM employees WHERE employee_id = (SELECT employee_id FROM employees);
B、DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_employees);
C、DELETE FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name ='Carrey');
D、DELETE * FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE last_name ='Carrey');
SNMP引擎是由哪些部分组成的？各部分的作用是什么？
将windows2000Sever中的系统性能设置为以直方图的形式先后记录系统中的实际内存，以Bytes为单位和虚拟内存。
