额定电流为50A的晶闸管可以流过()A的正弦半波有效值电流。
A. 75
B. 90
C. 100
D. 125
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如下哪种方式对于中小企业来讲是开展电子商务的最佳选择?()
A. 使用第三方平台
B. 单纯邮件营销
C. 自建企业网站
D. 购进专业的myalibaba或ERP系
You have a large amount of historical data in an operating system file. Some analysts in your organization need to query this data. The file is too large to load into your current database. Which is the most effective method to accomplish the task?()
A. Upgrade the hardware/memory to accommodate the data.
B. Load the data into your database by using the PARALLEL clause.
C. Give analysts DBA privilege, so that they can query DBA_EXTERNAL_TABLE
D. Use an external table so you can have the metadata available in your database, but leave the data in the operating system files.
干空气和水蒸气的混和气体称为湿空气,湿空气中水蒸气的含量很多。
A. 正确
B. 错误
《供电营业规则》第三十四条规定:用户办理改压手续时,改为高一等级电压供电,超过原容量者,超过部分按()办理。