How many rows of piles are generally set up in freestyle skating competition? How many piles per row? A: row 5 and 25 B: rows 2 and 18 C: rows 1 and 30 D: rows 3 and 20

If it is known that A is a 3×5 matrix, after executing A(:,1:2:3)=[], ( ). A: A becomes row vector B: A becomes 3 rows and 3 columns C: A becomes 3 rows and 2 columns D: A becomes 2 rows and 3 columns

下列选项中，能填入空白处1的代码是() A: dataStr.length != (rows-1) * (cols-1) B: dataStr.length != (rows-1) * cols C: dataStr.length != rows * cols D: dataStr.length != rows * (cols-1)

使用 turtle 库绘制树图形，效果如下图所示。阅读程序框架，补充横线处代码。import turtle as tdef tree(length,_________): #树的层次 if level <= 0: return t.forward(length) #前进方向画 length距离 t.left(45) tree(0.6*length,level–1) t.right(90) tree(0.6*length,level–1) t.left(45) t.backward(length) returnt.pensize(3)t.color('green')t.left(90)tree(100,6)[img=197x201]1803510ae669909.jpg[/img]

如果length=3，则以下代码：<;view wx:if="{{length >; 5}}">;1<;/view>;<;view wx:elif="{{length >; 2}}">;2<;/view>;<;view wx:else>;3<;/view>;的输出结果为（ ） A: 1 B: 2 C: 3 D: 4

获取页面中超链接数量的方法是（） A: document.links.length B: document.length C: document.links[1].length D: .document.links[0].length

<frameset rows=#>表示

If a is known to be a 2×3 matrix, then after executing a=a(:), ( ). A: a transforms to a column vector B: a transforms to 3 rows and 2 columns C: a transforms to 3 rows and 3 columns D: a transforms to 2 rows 3 and columns

rows是用来指定（）

<table rules=rows>,表示（ )。