Which two statements are true regarding the starting of the database instance using the following command？（） SQL>STARTUP UPGRADE [" It enables all system triggers."," It allows only SYSDBA connections."," It ensures that all job queues remain active during the upgrade process."," It sets system initialization parameters to specific values that are required to enable database upgrade scripts to be run."]
我国法定计量单位中共有（）个基本单位。 ["4","5","6","7"]
采用抵押方式担保时，债务人不按照合同约定的期限履行债务时，债权人有权依法留置该财产。
简述园长的角色。
垄断的基本类型有哪些？
公园
