单项选择题

下面的哪些程序段可能导致错误 ( )
Ⅰ: String s = "Gone with the wind";
String t = "good ";
String k = s + t;
Ⅱ: String s = "Gone with the wind";
String t;
t = s[3] + "one";
Ⅲ: String s = "Gone with the wind";
String standard = s.toUpperCase();
Ⅳ: String s = "home directory";
String t = s-"directory":

A．Ⅱ、Ⅲ
B．Ⅱ、Ⅳ
C．Ⅰ、Ⅳ
D．Ⅲ、Ⅳ

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单项选择题

下面程序的输出结果是( )。 public class Sun public static void main(String args[ ]) int n=4 ,sum=0; while (n＞0) sum+=n; n--; System.out.println( sum is +sum);

A．sum is 10
B．sum is 4
C．10
D．4

单项选择题

设有如下程序： import java.util.*; public class Sun public static void main(String args[ ]) int score; String a; Random r=new Random(); score=r.nextInt(4)+5; switch(score) case 0: a= E ; break; case 1: a= D ; break; case 2: a= C ; break; case 3: a= B ; break; default: a= A ; System.out.println(

A．;

程序运行的结果是( )。A) a="A"
B．aa"E" a="A"
C．a="E"
D．a="C"

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