题目内容

蓄电池在()向用电设备供电。

A. 发电机不工作或输出电压过低时
B. 起动发动机时
C. 发电机短时间超载时
D. 蓄电池存电不足时

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集线器与交换机的基本功能相同。

A. 正确
B. 错误

TPS系统中标准报表中PV值可以是()或()

A. 当前值,历史数据
B. 实时值,当前值
C. 前一时刻值,当前值
D. 实时值,前一时刻值

按照证据材料的来源不同,可以将其分为()和()。

You added a PHONE_NUMBER column of NUMBER data type to an existing EMPLOYEES table. The EMPLOYEES table already contains records of 100 employees. Now, you want to enter the phone numbers of each of the 100 employees into the table. Some of the employees may not have a phone number available. Which data manipulation operation do you perform? ()

A. MERGE
B. INSERT
C. UPDATE
D. ADD
ENTER
F. You cannot enter the phone numbers for the existing employee records.

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