名词解释题絮语xù yǔ
名词解释题
絮语xù yǔ
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下列哪些代码段是正确的?() A.X x=new X();Y y=new Y();Z z=new Z();y=(Y)x;B.X x=new X();Y y=new Y();Z z=new Z();x=(X)y;C.X x=new X();Y y=new Y();Z z=new Z();Z=(Z)x;D.X x=new X();Y y=new Y();Z z=new Z();W w=(W)x;
( 52 )下列关于函数依赖和多值依赖的叙述中,哪些是不正确的?I . 若 X → Y, 则 X →→ Y Ⅱ .若 X →→ Y, 则 X → YⅢ .若 Y ? X, 则 X → Y Ⅳ .若 Y ? X, 则 X →→ YⅤ .若 X → Y, Y ’ ? X, 则 X → Y ’ Ⅵ .若 X →→ Y, Y ’ ? Y, 则 X →→ Y ’A ) Ⅱ 和 ⅣB ) Ⅰ 、 Ⅲ 和 ⅣC ) Ⅱ 和 ⅥD ) Ⅳ 和 Ⅵ
(53)下列关于函数依赖和多值依赖的叙述中,( )是不正确的。Ⅰ、若X→Y,则X→→Y Ⅱ、若X→→Y,则X→YⅢ、若Y í X,则X→Y Ⅳ、若Y í X,则X→→YⅤ、若X→Y,Y* ì Y,则X→Y* Ⅵ、若X→→Y,Y*ìY,则X→→Y*A)仅Ⅱ和ⅣB)仅Ⅰ、Ⅱ和ⅣC)仅Ⅱ和ⅥD)仅Ⅳ、Ⅴ和Ⅵ
下列关于部分函数依赖的叙述中,( )是正确的?A)若X→Y,且存在Y的真子集Y ’,X→Y ',则称Y对x部分函数依赖B)若X→Y,且存在Y的真子集Y‘,X→Y ',则称Y对x部分函数依赖C)若X→Y,且存在X的真子集X',X'→Y,则称Y对x部分函数依赖D)若X→Y,且存在X的真子集X',X'→Y,则称Y对x部分函数依赖
设 X="11" , Y="1122" ,下列表达式结果为假的是A)NOT(X==y)AND(X$ Y )B)NOT(X$Y)OR(X ◇ Y)C)NOT( X =Y)D)NOT(X $ Y)
以下程序运行后的输出结果是 ______。 Sub add(x,y) x=x+y Print "x=";x;",y=";y End Sub Private Sub Command1_Click() x=1 y=1 Call add((x),(y)) Print"x="; x;",y=";y End SubA.x=1,y=1 x=2,y=2B.x=2,y=1 x=1,y=1C.x=1,y=1 x=1,y=1D.x=2,y=1 x=2,y=1
下面语句正确的是A.If xy Then y=x^3B.If xy Then y=x3C.If x 下面语句正确的是A.If x<3 * y And x>y Then y=x^3B.If x<3 * y And x>y Then y=x3C.If x<3 * y:x>y Then y=x^3D.If x<3 * y And x>y Then y=x* *3
表示关系x≥y≥z应使用C语言表达式()A.(x>=y)(y>=z)B.(x>y)AND(y>z)C.x>=y>=zD.(x>=y)(y>=z)B.(x>y)AND(y>z)C.x>=y>=zD.(x>=y)(y>=2)
下列函数定义不正确的是 ( )A.int max { int x y,z; z=x>y? x: y }B.int max(x,y) int x,y; { int z; z=x>y? x:y; return(z) }C.int max(x,y) { int x,y z; z=x>y? x: y; return(z); }D.int max( ) {}
与y=(x>0? 1:x0)y=1 else if(x 与y=(x>0? 1:x<0? -1:0);的功能相同的if语句是A.if(x>0)y=1 else if(x<0)y=-1; else y=O;B.if(x) if(x>0)y=1; else if(x<0)y=-1;C.y=-1; if(x) if(x>0)y=1; else if(x==0)y=0; else y=-1;D.y=0; if(x>=0) if(x>0)y=1; else y=-1;
与y=(x>0?1:x0)y=1; else if(x 与y=(x>0?1:x<0?-1:0):的功能相同的if语句是( )A.if(x>0)y=1; else if(x<0)y=-1; else y=0; else y=0;B.if(x) if(x>0)y=1; else if(x<0)y=-1;C.y=-1; if(x) if(x>0)y=1; else if(x==0)y=0; else y=-1;D.y=0; if(x>=0) if(x>0)y=1; else y=-1:
下列语句正确的是A.IfXY Then Y=X^3B.IfXY Then Y=X3C.IfXY Then 下列语句正确的是A.IfX<3*Y And X>Y Then Y=X^3B.IfX<3*Y And X>Y Then Y=X3C.IfX<3*Y:X>Y Then Y=X^3D.IfX<3*Y And X>Y Then Y=X**3
下列( )项是在D={(x,y)|x2+y2≤1,x≥0,y≥0)上的连续函数f(x,y),且f(x,y)=3(x+y)+16xy。A.f(x,y)=3(x+y)+32xyB.f(x,y)=3(x+y)-32xyC.f(x,y)=3(x+y)-16xyD.f(x,y)=3(x+y)+16xy
A.f(-x,y)=f(x,y),f(x,-y)=-f(x,y)B.f(-x,y)=f(x,y),f(x,-y)=f(x,y)C.f(-x,y)=-f(x,y),f(x,-y)=-f(x,y)D.f(-x,y)=-f(x,y),f(x,-y)=f(x,y)
已知y1(X)与y2(x)是方程:y" + P(x)y'+Q(x)y = 0的两个线性无关的特解,y1(x)和y2(x)分别是方程y"+P(x)y'+Q(x)y=R1(x)和y"+p(x)+Q(x)y=R2(x)的特解。那么方程y"+p(x)y'+Q(x)y=R1(x)+R2(x)的通解应是:A. c1y1+c2y2B. c1Y1(x) +c2Y2 (x)C. c1y1+c2y2 +Y1(x)D. c1y1+c2y2 +Y1 (x) +Y2 (x)
已知y1(x)和y2(x)是方程y''+p(x)y'+Q(x)y=0的两个线性无关的特解, Y1(x)和Y2 (x)分别是方程y''+p(x)y'+Q(x)y=R1(x)和y''+p(x)y'+Q(x)y=R2(x)的特解。那么方程y''+p(x)y'+Q(x)y=R1(x)y+R2(x)的通解应是:A. c1y1+c2y2B. c1Y1(x)+c2Y2(x) C. c1y1+c2y2+Y1(x) D. c1y1+c2y2+Y1(x)+Y2(x)
若y2(x)是线性非齐次方程y'+p(x)y=q(x)的解,y1(x)是对应的齐次方程y'+p(x)y=0的解,则下列函数也是y'+p(x)y=q(x) 的解的是( )。A.y=Cy1(x)+y2(x) B. y=y1(x)+Cy2(x)C.y=C[y1(x)+y2(x)] D.y=Cy1(x)-y2(x)
在图形指定位置加标注命令是()A、title(x,y,‟y=sin(x)‟);B、xlabel(x,y,‟y=sin(x)‟);C、text(x,y,‟y=sin(x)‟);D、legend(x,y,‟y=sin(x)‟);
若y2(x)是线性非齐次方程y′+P(x)y=Q(x)的解,y(x)是对应的齐次方程y′+P(x)y=0的解,则下列函数中哪一个是y′+P(x)y=Q(x)的解()?A、y=cy1(x)+y2(x)B、y=y1(x)+c2y2(x)C、y=c[y1(x)+y2(x)]D、y=c1y(x)-y2(x)
下列选项中,能正确地将x和y两个变量中的数据进行交换的表达式是()。A、x=x+y y=y+x x=x+yB、x=x+y y=x-y x=x-yC、x=x+y y=y-x x=x-yD、x=x-y y=x-y x=y-x
单选题要使E[Y-(aX+b)]2达到最小,则常数a=( )。b=( )。Aa=Cov(X,Y)/D(X);b=E(Y)-[E(X)Cov(X,Y)/D(X)D(Y)]Ba=Cov(X,Y)/D(X);b=E(Y)-[E(X)Cov(X,Y)/D(X)]Ca=Cov(X,Y);b=E(Y)-[E(X)Cov(X,Y)/D(X)]Da=Cov(X,Y);b=E(Y)-[E(X)Cov(X,Y)/D(X)D(Y)]
单选题下列选项中,能正确地将x和y两个变量中的数据进行交换的表达式是()。Ax=x+y y=y+x x=x+yBx=x+y y=x-y x=x-yCx=x+y y=y-x x=x-yDx=x-y y=x-y x=y-x
单选题已知y1(x)与y2(x)是方程y″+P(x)y′+Q(x)y=0的两个线性无关的特解,Y1(x)和Y2(x)分别是是方程y″+P(x)y′+Q(x)y=R1(x)和y″+P(x)y′+Q(x)y=R2(x)的特解。那么方程y″+P(x)y′+Q(x)y=R1(x)+R2(x)的通解应是:()Ac1y1+c2y2Bc1Y1(x)+c2Y2(x)Cc1y1+c2y2+Y1(x)Dc1y1+c2y2+Y1(x)+Y2(x)
单选题下列关于函数依赖和多值依赖的叙述中,()是不正确的。 Ⅰ、若X→Y,则X→→Y Ⅱ、若X→→Y,则X→Y Ⅲ、若YÍX,则X→Y Ⅳ、若YÍX,则X→→Y Ⅴ、若X→Y,Y*ÌY,则X→Y* Ⅵ、若X→→Y,Y*ÌY,则X→→Y*A仅Ⅱ和ⅣB仅Ⅰ、Ⅱ和ⅣC仅Ⅱ和ⅥD仅Ⅳ、Ⅴ和Ⅵ