题目内容

关于脑膜炎奈瑟菌的感染,错误的是 ( )

A. 引起菌血症
B. 主要经飞沫传染
C. 6个月内婴儿易感染
D. 主要是脂寡糖致病
E. 流行期间儿童可服用磺胺类药物预防

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设随机变量服从参数为2的指数分布,那么随机变量的方差为( )

A. 2
B. 4
C. 1/2
D. 1/4

在java中,已定义了两个接口B和C,要定义一个实现这两个接口的类,以下语句正 确的是 ( )

A. interface A extends B,C
B. interface A implements B,C
C. class A implements B,C
D. class A implements B,implements C

类间的继承关系是( )

A. 单重的
B. 多重的
C. 既可以单重又可以多重
D. 不能继承

阅读下面的程序,其中正确的是()class person {String name;String nickName;public person(String a, String b) {name=a;nickName=b;}public String toString() {return name+" nickName="+nickName;}}public class employee extends person {String rank;public employee (String a, String b, String c) {super(a, b);rank=c;}public String toString(){return name+" nickName="+nickName+" rank="+rank ;}public public static void main(String[] args) {person one=new person("Wang", "Zhang");person two=new employee("Bob", "Tom", "manager");employee three =new employee("Jack", "David", "CEO");System.out.println(" one is "+ one.toString());System.out.println(" two is "+ two.toString());System.out.println(" three is "+ three.toString());}}

A. 编译时会出现错误
B. 运行时会出现错误
C. 运行结果是: one is Wang nickName=Zhang two is Bob nickName=Tom rank=manager three is Jack nickName=David rank=CEO
D. 运行结果是: one is Wang nickName=Zhang two is Bob nickName=Tom three is Jack nickName=David rank=CEO

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