题目内容

浓硫酸与金属反应时,除生成金属硫酸盐外,还原产物肯定是SO?。

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Whatwillbewrittentothestandardoutputwhenthefollowingprogramisrun?()
classBase{inti;Base(){
add(1);
}
voidadd(intv){i+=v;}
voidprint(){System.out.println(i);}
}
classExtensionextendsBase{Extension(){add(2);}
voidadd(intv){i+=v*2;}}
publicclassQd073{
publicstaticvoidmain(Stringargs[]){bogo(newExtension());}
staticvoidbogo(Baseb){b.add(8);b.print();
}
}

GivenafileGrizzlyBear.java:
1.packageanimals.mammals;
2.
3.publicclassGrizzlyBearextendsBear{
4.voidhunt(){
5.Salmons=findSalmon();
6.s.consume();
7.}
8.}
andanotherfile,Salmon.java:
1.packageanimals.fish;
2.
3.publicclassSalmonextendsFish{
4.voidconsume(){/*dostuff*/}
5.}
Assumebothclassesaredefinedinthecorrectdirectoriesfortheftpackages,andthattheMammalclasscorrectlydefinesthefindSalmon()method.Whichtwochangesallowthiscodetocompilecorrectly?()

天然气的主要成分是CO。

1.publicclassA{
2.publicvoidmethod1(){
3.Bb=newB();
4.b.method2();
5.//morecodehere
6.}
7.}
1.publicclassB{
2.publicvoidmethod2(){
3.Cc=newC();
4.c.method3();
5.//morecodehere
6.}
7.}
1.publicclassC{
2.publicvoidmethod3(){
3.//morecodehere
4.}
5.}
Given:
25.try{
26.Aa=newA();
27.a.method1();
28.}catch(Exceptione){
29.System.out.print(”anerroroccurred”);
30.}
WhichtwoaretrueifaNullPointerExceptionisthrownonline3ofclassC?()

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