A firm operating in a competitive market will stay in business in the short run so long as the market price exceeds the firm’s average total cost; otherwise, the firm will shut down.
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All competitive firms earn zero economic profit in both the short run and the long run.
A. 对
B. 错
在SQL Server2000中,当表中的数据被修改时,系统自动执行的数据库对象____
A. 存储过程
B. 触发器
C. 视图
D. 表
激活DML触发器的更新数据语句,有效选项是()。
A. INSERT
B. UPDATE
C. DELETE
D. SELECT
在执行对表“Book”的更新操作时,如果希望不执行该操作,而是执行其他操作,则应该创建()类型的DML触发器。
A. FOR
BEFORE
C. AFTER
D. INSTEAD OF