执行以下语句的结果：dict1={"x":1,"y":2,"z":3}dict2={"x":4,"a":5}dict1.update(dict2) A: {"x":1,"y":2,"z":3,"x":4,"a":5} B: {"x":4,"a":5,"x":1,"y":2,"z":3} C: 有重复项，结果有误！ D: {"x":4,"y":2,"z":3,"a":5}

x=2,y=5,z=3 (x>y)+z*4=?

图示的力分别在x、y、z三轴上的投影为（） A: X=2√2P/5，Y=3√2P/10，Z=√2P/2 B: X=2√2P/5，Y=-3√2P/10，Z=-√2P/2 C: X=-2√2P/5，Y=3√2P/10，Z=√2P/2 D: X=-2√2P/5，Y=-3√2P/10，Z=√2P/2

图示的力分别在x、y、z三轴上的投影为（ ）。[img=277x232]1786983f925fb81.png[/img] A: X=2Ö2P/5, Y=3Ö2P/10, Z=Ö2P/2 B: X=2Ö2P/5, Y= - 3Ö2P/10, Z= - Ö2P/2 C: X= - 2Ö2P/5, Y=3Ö2P/10, Z=Ö2P/2 D: X= - 2Ö2P/5, Y= - 3Ö2P/10, Z=Ö2P/2

图示的力分别在x、y、z三轴上的投影为（ ）[img=260x229]1786983fb13c0a2.png[/img] A: X= - 3Ö2P/10, Y= 2Ö2P/5, Z= - Ö2P/2 B: X= - 2Ö2P/5, Y= 3Ö2P/10, Z= - Ö2P/2 C: X= 3Ö2P/10, Y= - 2Ö2P/5, Z= - Ö2P/2 D: X= 2Ö2P/5, Y= 3Ö2P/10, Z= - Ö2P/2

设x=2以及y=3，下面代码的输出结果是。if (x >; 2)if（y >; 2）{int z = x + y;System.out.println("z is " + z) ;}else{System.out.println("x is " + x) ;} A: x is 2 B: z is 5 C: x is 5 D: 无输出

函数 [img=197x96]1803dbfc46ca27a.png[/img]表示的曲面称为椭圆锥面，绘制这个曲面的程序是： A: s=-5:0.1:5;t=-5:0.1:5;[x, y]=meshgrid(s, t);z=sqrt(x.^2+y.^2);mesh(x,y,z) B: a=3;b=2;s=-5:0.1:5;t=-5:0.1:5;[x, y]=meshgrid(s, t);z=sqrt(x.^2/a/a+y.^2/b/b);mesh(x, y, z) C: a=3;b=2;s=-5:0.1:5;t=-5:0.1:5;[x, y]=meshgrid(s, t);z=sqrt(x.^2/a*a+y.^2/b*b);mesh(x, y, z) D: a=3;b=2;s=-5:0.1:5;t=-5:0.1:5;[x, y]=meshgrid(s, t);z=sqrt(x^2/a/a+y^2/b/b);mesh(x, y, z);

已知int x=1，y=2，z=3；执行if(x>y) z=x；x=y；y=z；后x，y，z的值为（ ） A: x=1，y=2，z=3 B: x=2，y=3，z=3 C: x=2，y=3，z=1 D: x=2，y=3，z=2

已知int x=1,y=2,z=3;以下语句执行后x,y,z的值是( ). if(x>y) z=x; x=y; y=z; A: x=1, y=2, z=3 B: x=2, y=3, z=3 C: x=2, y=3, z=1 D: x=2, y=3, z=2

设x=2,y=3,z=4,k=5，则表达式“x 2