定冷水泵进出口差压小于()时,差压开关闭合发出泵停运信号并联锁()。
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探头扫查的进行一是要保证试件的整个须检测区有足够的声束覆盖以免漏检。
A. 正确
B. 错误
在西欧国家中,实行总统制最为典型的国家是:()法国现任总统为萨科齐。
A. 德国
B. 法国
C. 瑞士
D. 奥地利
E601型蒸发器主要由蒸发桶、水圈、测针和溢流桶四个部分组成。蒸发桶是蒸发器的主体部分,用于盛装蒸发观测()。
A. 气
B. 水
C. 油
D. 土
The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER (4) NOT NULL CUSTOMER_NAME VARCHAR2 (100) NOT NULL STREET_ADDRESS VARCHAR2 (150) CITY_ADDRESS VARHCAR2 (50) STATE_ADDRESS VARCHAR2 (50) PROVINCE_ADDRESS VARCHAR2 (50) COUNTRY_ADDRESS VARCHAR2 (50) POSTAL_CODE VARCHAR2 (12) CUSTOMER_PHONE VARCHAR2 (20) The CUSTOMER_ID column is the primary key for the table. You need to determine how dispersed your customer base is. Which expression finds the number of different countries represented in the CUSTOMERS table?()
A. COUNT(UPPER(country_address))
B. COUNT(DIFF(UPPER(country_address)))
COUNT(UNIQUE(UPPER(country_address)))
D. COUNT DISTINTC UPPER(country_address)
E. COUNT(DISTINTC (UPPER(country_address)))