【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.
【单选题】Which of the following is a logical connected set of fields that describes a person, place or a thing?
【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。...