定义一个CPU类，包含等级(rank)、频率(freqlaency)、电压(voltage)等属性，有两个公有成员函数run、stop。其中，rank为枚举类型CPU—Rank，定义为enum CPU—Rank

{Pl=1，P2，P3，P4，P5，P6，P7}，frequency为单位是MHz的整型数，voltage为浮点型的

电压值。观察构造函数和析构函数的调用顺序。

--(1) the definition of a CPU class, including level (rank), frequency (have), voltage (the) attribute, two public member function, which rank 6), stop for enumeration type CPU_ rank, defined as enum CPU_ rank (P1 = 1, P2, P3, mp4, system, what do, even if have, for the unit is MHz integer, the type of voltage value for floating point. The structures observed function and destructor call sequence.