vector的引用无效？修改不了成员变量的vector解决办法

vector的引用无效？修改不了成员变量的vector
vector的引用无效？修改不了成员变量的vector，求解决方法。

C/C++ code

#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;}