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【单选题】
不允许数据库表在指定列上具有相同的值,但允许有空值,属于( )约束。A.
DEFAULT
B.
CHECK
C.
PRIMARY KEY
D.
FOREIGN KEY
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【简答题】Direction: Here are some examples in everyday language. Transform them into sentences in scientific language by nominalising the underlined parts.Because bacteria genes are incredibly adaptable, there...
【单选题】G negative bacteria are usually not sensitive to penicillin, because
A.
they do not have teichoic acids in peptidoglycan
B.
they do not have side chains in peptidoglycan
C.
they do not have NAG-NAM backbones in peptidoglycan
D.
they do not have cross-bridge in peptidoglycan
【多选题】屋面坡度大于25%时，防水卷材应当（）
A.
平行屋脊铺贴
B.
上下卷材宜垂直铺贴
C.
卷材采用满粘法固定
D.
卷材采用钉压固定
E.
相邻两幅卷材短边搭接缝应错开，且不得小于200mm
【简答题】二辊式定、减径机主传动形式有 和单独传动两种。
【单选题】According to the researchers, cream sours faster than butter because bacteria ______
A.
are mom evenly distributed in cream
B.
multiply more easily in cream than in butter
C.
live on less fat in cream than in butter
D.
produce less waste in cream than in butter.
【单选题】According to the researchers, cream sours faster than butter because bacteria ______.
A.
are more evenly distributed in cream
B.
multiply more easily in cream than in butter
C.
live on less fat in cream than in butter
D.
produce less waste in cream than in butter
【简答题】According to the researchers, cream sours fast than butter because bacteria ________. A) are more evenly distributed in cream B) multiply more easily in cream than in butter C) live on less fat in cre...
【单选题】According to the researchers, cream sours faster than butter because bacteria ______.
A.
are more evenly distributed in cream
B.
multiply more easily in cream than is butter
C.
live on less fat in cream than in butter
D.
produce less waste in cream than in butter
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