浪涌保护器：通过抑制瞬态过电压以及（）来保护设备的装置。它至少含有一个非线性元件。 接地线。 接地引下线。 接地汇集排。 旁路浪涌电流。
You work as a database administrator for Certkiller .com. You want to configure database backups to be run automatically. Which tool or utility would you use to achieve this？ （） The DBMS_JOB package。 The BACKUP_JOB package。 The DBMS_BACKUP_RESTORE package。 The calendar tool in the Operating System （OS）。 The backup scheduler in Enterprise Manager （EM）。 The DBMS_BACKUP_SCHEDULER packager inline mode。
固体表面的湿润性与湿润角
Examine the data in the EMPLOYEES and DEPARTMENTS tables. EMPLOYEES LAST_NAME DEPARTMENT_ID SALARY Getz 10 3000 Davis 20 1500 Bill 20 2200 Davis 30 5000 Kochhar 5000 DEPARTMENTS DEPARTMENT_ID DEPARTMENT_NAME 10 Sales 20 Marketing 30 Accounts 40 Administration You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?（） SELECT last_name, department_name FROM employees , departments(+);。 SELECT last_name, department_name FROM employees JOIN departments(+);。 SELECT last_name, department_name ON (e. department_ id = d. departments_id); FROM employees(+) e JOIN departments d。 SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);。 SELECT last_name, department_name FROM employees(+) , departments ON (e. department _ id = d. department _id);。 SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e. department _ id = d. department _id)。
脱丁烷塔丁烷产品中C3含量偏高可能是（） 脱丁烷塔底至沸温度高。 脱丁烷塔顶回流小。 脱丙烷塔底再沸温度偏低。
影响消费者心理及行为的外部条件有（）
