vector的引用无效？修改不了成员变量的vector解决办法

#include <iostream>
#include<vector>
#include<string>
using namespace std;
class A
{
public:
    vector<string> & getVec(){return mA;}
    void print(){
        for(vector<string>::iterator i= mA.begin(); i!=mA.end(); ++i)
        {
            cout<<*i<<" ";
        }
    }
private:
    vector<string > mA;
};
int main()
{
    A b;
    vector<string > c = b.getVec();
    c.push_back("as");
    c.push_back("a");
    for(vector<string>::iterator i= c.begin(); i!=c.end(); ++i)
    {
        cout<<*i<<" ";
    }
    b.print();
    return 0;
}