在集中控制方式中,如何提高系统的可靠性?
参考答案:
系统应采用双机配置,双机集中控制又可分为话务分担和主备用方式。
比较银和铜的金属活动性强弱,可选用的药品是( )
A.硝酸汞溶液
B.稀硫酸
C.硫酸锌溶液
D.稀盐酸
-- yesterday?
-- Friday.[ ]
A. What time was it
B. What day was it
C. What was the date
D. What was the day