【判断题】转差率s是分析异步电动机的运行性能的一个重要参数,当电动机转速越快时,则对应的转差率也就越大。( )
【单选题】What is the candidate key of a relational database? ( )
A.
Fields from multiple tables that are used for sorting records
B.
A set of fields in a table used to identify a record uniquely
C.
A field with a constraint placed on it
D.
A set of fields that have no data in them
【简答题】combine the sentences in each of the following groups into one, using parallel constructions wherever possible. A Black people in America have been neglected for years B Black people in America have b...
【单选题】What did the expansion of fields in the First World War lead to?
D.
Extinction of rattlesnakes.
【简答题】A Black people in America have been neglected for years B Black people in America have been underestimated for years C. Their recent accomplishments in a variety of fields have made "black power"real。...
【多选题】在Windows中,如果数据被储存在“剪贴板”中,可能执行过的操作是( )