【单选题】A block whose mass m = 680g is fastened to a spring whose spring constant k = 65N/m. The block is pulled a distance x = 11cm from its equilibrium position at x = 0 on a frictionless surface and releas...
【单选题】子类和父类的定义如下: class A { int v1=10; int v2=10; public A() {} public A(int v1) { super(); } public void m1() { System.out.println("A m1"); } public void m2() { System.out.println("A m2"); } } class B exte...