/// <summary>
/// 提供Clone方法调用的私有构造函数，以便克隆“工作经历”的数据
/// </summary>
/// <param name="work"></param>
private Resume(WorkExperience work)
{
this.work = (WorkExperience)work.Clone();
}
public Resume(string name)
{
this.name = name;
//在简历类实例化时候同时实例化“工作经历”
work = new WorkExperience();
}