99.Which two statements are true regarding Oracle Data Pump? (Choose two.)

99.Which two statements are true regarding Oracle Data Pump? (Choose two.)
A.EXPDP and IMPDP are the client components of Oracle Data Pump.
B.DBMS_DATAPUMP PL/SQL packages can be used independently of the Data Pump clients.
C.Oracle Data Pump export and import operations can be performed only by users with the SYSDBA privilege.
D.Oracle Data Pump imports can be done from the export files generated in the export utility of previous versions.
E.EXPDP and IMPDP use the procedures provided by DBMS_METADATA to execute export and import commands.
答案：AB
参考：
https://docs.oracle.com/cd/B19306_01/server.102/b14215/dp_overview.htm#i1010293

https://docs.oracle.com/cd/E24693_01/server.11203/e22490/dp_overview.htm

Oracle Data Pump is made up of three distinct parts:
1.The command-line clients, expdp and impdp
  2.The DBMS_DATAPUMP PL/SQL package (also known as the Data Pump API)
  3.The DBMS_METADATA PL/SQL package (also known as the Metadata API)
因此A正确，B正确，E是错误的  
expdp、impdp
1.需要使用系统目录，oracle默认会创建一个DATA_PUMP_DIR的目录
2.需要把目录的权限授予expdp的用户
高版本的可以导入到低版本的，低版本不可以导入高版本中，需要注意的是从高版本导出的时候需要指定低版本的版本号
expdp username/password directory=dump_test dumpfile=data.dmp  version=11.1.0.0.0 --这里指定低版本的版本号(导出的版本是11.2.0.4.0)
然后正常impdp就可以了，因此排除D
SQL> show user;
USER is "SYS"
SQL> create user datauser identified by datauser;
User created.
SQL> grant connect,resource to datauser;
Grant succeeded.
SQL> grant  read,write on directory data_pump_dir to datauser;
Grant succeeded.
SQL> select DIRECTORY_PATH from dba_directories where directory_name='DATA_PUMP_DIR';
DIRECTORY_PATH
--------------------------------------------------------------------------------
/u01/oracle/admin/wahaha3/dpdump/
SQL> quit
[oracle@wahaha3 ~]$ cd /u01/oracle/admin/wahaha3/dpdump/
[oracle@wahaha3 dpdump]$ expdp datauser/datauser directory=DATA_PUMP_DIR dumpfile=data.dump schemas=datauser logfile=data.log;
Export: Release 11.2.0.3.0 - Production on Sun Jul 24 22:20:06 2016


Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.


Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
Starting "DATAUSER"."SYS_EXPORT_SCHEMA_01":  datauser/******** directory=DATA_PUMP_DIR dumpfile=data.dump schemas=datauser logfile=data.log 
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 0 KB
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Master table "DATAUSER"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for DATAUSER.SYS_EXPORT_SCHEMA_01 is:
  /u01/oracle/admin/wahaha3/dpdump/data.dump
Job "DATAUSER"."SYS_EXPORT_SCHEMA_01" successfully completed at 22:21:15
[oracle@wahaha3 dpdump]$ ls -lt
total 424
-rw-r--r--. 1 oracle oinstall   1293 Jul 24 22:21 data.log
-rw-r-----. 1 oracle oinstall 147456 Jul 24 22:21 data.dump
--排除C