分离极性强的成分,宜选用活性低的吸附剂,用()溶剂做洗脱剂,分离极性弱的成分,宜选用活性()的吸附剂,用()溶剂做洗脱剂。
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The EMPLOYEES table contains these columns: LAST_NAME VARCHAR2 (25) SALARY NUMBER (6,2) COMMISSION_PCT NUMBER (6) You need to write a query that will produce these results: 1. Display the salary multiplied by the commission_pct. 2. Exclude employees with a zero commission_pct. 3. Display a zero for employees with a null commission value. Evaluate the SQL statement: SELECT LAST_NAME, SALARY*COMMISSION_PCT FROM EMPLOYEES WHERE COMMISSION_PCT IS NOT NULL; What does the statement provide? ()
All of the desired results
B. Two of the desired results
C. One of the desired results
D. An error statement
1956年5月2日,()在最高国务会议上提出了“百花齐放,百家争鸣”的方针(即双百方针),5月26日,中共中央宣传部长陆定一在题为《百花齐放,百家争鸣》的报告中对这一方针作了阐释。
A. 周恩来
B. 毛泽东
C. 董必武
D. 郭沫若