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问题 单项选择题

设有如下三个关系表：


下列操作中正确的是( )

A．T=R∩S
B．T=R∪S
C．T=R×S
D．T=R／S

答案

参考答案：C

解析： 关系代数中的集合运算有并、差、交和笛卡儿积4种。根据本题关系T中的元组可知，它是由关系R和关系S进行笛卡儿积运算得到的。

单项选择题 A1/A2型题

按附着体位置及结构分类，覆盖义齿附着体可分为（）

A.刚性附着体、非刚性附着体、弹性附着体

B.根上附着体、根内附着体、杆附着体、磁性附着体

C.根上附着体、根内附着体

D.杆附着体、磁性附着体

E.以上都不对
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单项选择题

Timberwolves are Marching to a New Tune
森林狼按新的节拍在前进


For the past seven years，Kevin McHale has struggled to put the right combination around his superstar，Kevin Garnett.McHale brought in dozens of players to complement his main man，but in the end the Timberwolves always looked like the’70s band Wings-one star(Paul McCartney) and a bunch of people nobody noticed.
With apologies to all of you who still are jamming to"Silly Love Songs，"Wings never could live up to the Beatles.They didn’t have the star power.
Well，McHale finally has found his own personal John Lennon and Ringo Starr，and their names are Sam Cassell and Latrell Sprewell.The two veteran guards have given the Wolves an edge they’ve never had before，and suddenly Garnett doesn’t have to do it all by himself. Wednesday in San Antonio，Garneu struggled at the start，found himself in foul trouble and never really got into the flow of the game.As all superstars do，he still managed to put up good numbers(22 points and 10 rebounds).But Gamett never found his groove.and he certainlv didn’t control the game.
Fortunately for Kevin Garnett，he didn’t have to.Cassell，who has hit more big shots than anyone this side of Reggie Miller，came through with a huge game.Displaying his uncanny knack for creating his own midrange shots，Cassell riddled the Spurs’defense for 33 points including several clutch buckets in the fourth quarter.
Some guys like to take big shots.Cassell needs them.When the game gets tight and his.team needs a basket，Sam’s eyes light up and he enters another world.He lusts for moments like those. Sprewell also had a major impact in Wednesday’s victory，scoring 24 points and sealing the win with a steal and a highlight-reel slam．He is playing with amazing energy and zeal，and a touch of attitude that we haven’t seen from Wolves players in the past.Together.the"Big Three" have become a major force that has to rank with any combination in the league.
Wednesday’s victory in San Antonio epitomized the type of team that Minnesota has been all season.The Wolves defended well，scored 100 points against the league’s best defense．got major contributions from their bench and huge shots from their stars，and showed a resilience and confidence usually reserved for championship teams.
After several first-round flameouts，is this the year the Wolves finally make it over the hump in the playoffsIt’s only January，so we probably shouldn’t get ahead of ourselves.But the team I saw Wednesday night showed all the signs of being a major player in the NBA playoffs this spring.
If things fall just right for McHale，maybe he can finally stop fiddling with his roster and simply"Let It Be.\

The title of the passage"Timberwolves are marching to a new tune"means that______．

A．the team has changed from having to arrange a good combination of players around its only superstar into a new state in which more players are performing wonderfully
B．the team has changed from having to arrange a good combination of players around Kevin Gamett into a new combination of players around the new stars Lennon and Starr
C．the team has improved so much that it has entered a new stage
D．the team has organized demonstration with some musical instruments playing beautiful tunes
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