预测本国国际收支将出现逆差时,可以(),以达到国际收支平衡。
A. 调高外汇汇率,实行本币对外贬值
B. 调低外汇汇率,实行本币对外升值
C. 使外汇汇率不变,本币对外价值维持不变
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合格品混凝土路缘石吸水率不大于()%.
A. 6
B. 7
C. 8
D. 9
Examine the commands executed in the following sequence: 1:SQL> CREATE ROLE mgrrole; 2:SQL> GRANT create user,select any table,connect,resource TO mgrrole; 3:SQL> GRANT select,update ON sh.sales TO mgrrole; 4:SQL> CREATE ROLE ceo IDENTIFIED BY boss; 5:SQL> GRANT mgrrole,drop any table,create any directory TO ceo; 6:SQL> GRANT ceo TO mgrrole; Which statement is true about the above commands()
A. The commands execute successfully.
B. Command 6 produces an error because of circular role grant.
Command 5 produces an error because a role cannot be granted to another role.
D. Command 3 produces an error because the MGRROLE role already contains system privileges.
E. The table created by HR remains and HR still has the CREATE TABLE system privilege.
F. The table created by HR remains and HR can grant the CREATE TABLE system privilege to other users.
舵系中心线的确定采用拉线法,因为舵系中心线是垂直方向的,不存在因钢丝自重而产生绕度问题,精度容易保证。
A. 正确
B. 错误
直流系统升降功率前应确认功率设定值不小于当前系统允许的最小功率,且不能超过当前系统允许的最大功率限制。
A. 正确
B. 错误