对于以下递归函数f，调用函数f(2, ' 1', ' 2', ' 3')的输出结果是（ ）。void f(int n, char a, char b, char c){ if (n == 1) printf("%c->;%c#", a, b) ; else { f(n-1, a, c, b); printf("%c->;%c#", a, b); f(n-1, c, b, a); }} A: 1->;3#1->;2#3->;2# B: 3->;2#1->;2#1->;3# C: 1->;2#1->;3#3->;2# D: '1'->;'3'#'3'->;'2'#'1'->;'2'#

对于以下递归函数f，调用函数f(2, ' 1', ' 2', ' 3')的输出结果是（ ）。void f(int n, char a, char b, char c){ if (n == 1) printf("%c->%c#", a, b) ; else { f(n-1, a, c, b); printf("%c->%c#", a, b); f(n-1, c, b, a); }} A: 3->2#1->2#1->3# B: 1->2#1->3#3->2# C: '1'->'3'#'3'->'2'#'1'->'2'# D: 1->3#1->2#3->2#

Word中插入数学公式的方法是（）。 A: "插入"→"形状"→"公式" B: "开发工具"→"公式" C: "插入"→"公式"→"插入新公式" D: "引用"→"插入"→"公式"

下面语句中,正确的是( )。 A: printf("%c ","student"); B: printf("%c ","c"); C: printf("%s ",&a); D: printf("%s ","hello");

C语言空语句是由一个（ ）构成的。 A: 冒号":" B: 分号";" C: 逗号"," D: 句号"."

继续上题，为了程序编写简洁，要给数据框x中的6列重新命名为x1,x2,x3,x4,x5,x6,应该使用的命令是（） A: ColNames(x) <- c("x1","x2","x3","x4","x5","x6") B: Names(x) <- c("x1","x2","x3","x4","x5","x6") C: colnames(x) <- c("x1","x2","x3","x4","x5","x6") D: colname(x) <- c("x1","x2","x3","x4","x5","x6")

定义并初始化一个用于存放我们国家的四个直辖市的数组cityName，四个直辖市为：北京，上海，天津，重庆. 正确的是_________ A: String[] cityName=new String[4]{"北京","上海","天津","重庆"}; B: String[] cityName=new String[]{"北京","上海","天津","重庆"}; C: String[] cityName={"北京","上海","天津","重庆"}; D: String cityName = new String[4] { "北京", "上海", "天津", "重庆" };

R 语言中，代表注释语句起始的符号是（ ）。 A: "," B: ";" C: ":" D: " E: "

id选择器使用_______________进行标识，后面紧跟id名。 A: " B: " C: "&" D: "@" E: "$"

已知有一个名为names的空列表,如何向其中添加old_driver,rain,jack,shanshan,peiqi,black_girl 元素？ A: names.append("old_driver","rain","jack","shanshan","peiqi","black_girl") B: names.extend("old_driver","rain","jack","shanshan","peiqi","black_girl") C: names.insert("old_driver","rain","jack","shanshan","peiqi","black_girl") D: names.extend(["old_driver","rain","jack","shanshan","peiqi","black_girl"])