类Teacher和Student是类Person的子类； Person p; Teacher t; Student s; //p, t and s are all non-null. if（t instanceof Person) { s = （Student)t; } 最后一句语句的结果是：（)
A．将构造一个Student对象；
B．表达式是合法的；
C．表达式是错误的；
D．编译时正确，但运行时错误。
单选题The teacher-student _____ in China’s universities is much lower than that in the U.S.A rateB rankC ratioD range
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多选题定义字符数组正确的是（）。Achars[]=Student；Bchars[7]=Student；Cchars[7]={’S’，’t’，’u’，’d’，’e’，’n’，’t’}；Dchars[]={Student}；
单选题What is the teacher doing in terms of error correction?“ S: I go to the theatre last night．”T: You GO to the theatre last night?A．Correcting the student’s mistake.B．Hinting that there is a mistake.C．Encouraging peer correction.D．Asking the student whether he really went to the theatre．A AB BC CD D
多选题Which are syntactically valid statement at// point x？（） class Person { private int a； public int change（int m）{ return m； } } public class Teacher extends Person { public int b； public static void main（String arg[]）{ Person p = new Person（）； Teacher t = new Teacher（）； int i； // point x } }Ai = m；Bi = b；Ci = p.a；Di = p.change（30）；Ei = t.b.
单选题创建一个名为student的新类，保存新类的类库名称是mylib，新类的父类是Person，正确的命令是（ ）。A CREATE CLASS mylib OF student As PersonB CREATE CLASS student OF Person As mylibC CREATE CLASS student OF mylib As PersonD CREATE CLASS Person OF mylib As student
单选题对于下列代码： 1) class Person { 2} public void printValue(int i, int j) {//... } 3} public void printValue(int i){//... } 4} } 5) public class Teacher extends Person { 6} public void printValue（ ） {//... } 7} public void printValue(int i) {//...} 8} public static void main(String args[]){ 9} Person t = new Teacher（ ）; 10} t.printValue(10); 11} } 第10行语句将调用哪行语句？（）Aline 2Bline 3Cline 6Dline 7
单选题类Teacher和Student是类Person的子类； Person p； Teacher t； Student s； //p， t and s are all non-null. if（t instanceof Person） { s = （Student）t； } 最后一句语句的结果是：（）A将构造一个Student对象；B表达式是合法的；C表达式是错误的；D编译时正确，但运行时错误。
