单项选择题

6502电气集中，（）是用来区分黄灯与双黄灯显示的。
A、ZXJ
B、TXJ
C、DXJ
D、LXJ

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单项选择题

The EMPLOYEES table has these columns:LAST NAME VARCHAR2(35)SALARY NUMBER(8,2)HIRE_DATE DATEManagement wants to add a default value to the SALARY column. You plan to alter the table by using this SQL statement:ALTER TABLE EMPLOYEESMODIFY ( SALARY DEFAULT 5000);What is true about your ALTER statement?（）A.Column definitions cannot be altered to add DEFAULT values.B.A change to the DEFAULT value affects only subsequent insertions to the tablE.C.Column definitions cannot be altered at add DEFAULT values for columns with a NUMBER data typE.D.All the rows that have a NULL value for the SALARY column will be updated with the value 5000.

单项选择题

下列可引起肝细胞性黄疸的疾病是A. 原发性胆汁性肝硬化B. 蚕豆病C. 毛细胆管型病毒性肝炎D. 胆总管结石E. 中毒性肝炎

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