单项选择题 You want to use the automatic management of backup and recovery operations features for your database.Which configuration must you set?（）

多项选择题 Evaluate the following statements：   CREATE TABLE purchase_orders （po_id NUMBER（4），  po_date TIMESTAMP， supplier_id NUMBER（6）， po_total NUMBER（8，2），  CONSTRAINT order_pk PRIMARY KEY（po_id）） PARTITION BY RANGE（po_date）  （PARTITION Q1 VALUES LESS THAN （TO_DATE（？1-apr-2007？d-mon-yyyy？）， PARTITION Q2 VALUES LESS THAN  （TO_DATE（？1-jul-2007？d-mon-yyyy？），  PARTITION Q3 VALUES LESS THAN（TO_DATE（？1-oct - 2007？d-mon-yyyy？）， PARTITION Q4 VALUES LESS THAN （TO_DATE（？1-jan-2008？d-mon-yyyy？））；  CREATE TABLE purchase_order_items （po_id NUMBER（4） NOT NULL， product_id NUMBER（6） NOT NULL， unit_price NUMBER（8，2）， quantity NUMBER（8）， CONSTRAINT po_items_fk FOREIGN KEY  （po_id） REFERENCES purchase_orders（po_id）） PARTITION BY REFERENCE（po_items_fk）；   What are the two consequences of the above statements？（）

单项选择题 To accomplish user-managed backup for the USERS tablespace, you issued the following command to put the database in backup mode: SQL> ALTER TABLESPACE users BEGIN BACKUP; While copying the file to the backup destination a power outage caused the instance to terminate abnormally. Which statement is true about the next database startup and the USERS tablespace?（）