简述吗啡治疗心源性哮喘的作用机制。
An SMB customer is looking for a low cost， easy to install and configure， entry-level SAN solution to attach to five rack-mounted System x Servers. Which storage solution would be best for this customer？（） ["EXP3000 Local Attached Storage Enclosures","DS4000 Series storage solution","DS3000 Series Storage solution","DS4800 Storage Solutio"]
You are maintaining the PROD database of NetFx Corporation. You set the value of the SQL_TRACE parameter to TRUE. What will be the impact of this setting？（） [" The SQL trace facility will generate the performance statistics for all the SQL statements for an instance and write them in the USER_DUMP_DEST directory."," The SQL trace facility will generate the performance statistics for all the SQL statements for a session and write them in the USER_DUMP_DEST directory."," The SQL trace facility will generate the performance statistics for all the SQL statements for an instance and write them in the BACKGROUND_DUMP_DEST directory."," The SQL trace facility will generate the performance statistics for all the SQL statements for a session and write them in the BACKGROUND_DUMP_DEST directory."]
偿债能力
Which three SELECT statements displays 2000 in the format "$2,000.00"? （） [" SELECT TO CNAR(2000, '$#,###.##') FROM dual;"," SELECT TO CNAR(2000, '$0,000.00') FROM dual;"," SELECT TO CNAR(2000, '$9,999.00') FROM dual;"," SELECT TO CNAR(2000, '$9,999.99') FROM dual;"," SELECT TO CNAR(2000, '$2,000.00') FROM dual;"," SELECT TO CNAR(2000, '$N,NNN.NN') FROM dual"]
三角形接线时的线电流是星形接线时线电流的（）倍。
