有如下程序：#include ＜iostream＞using namespace std;class Base{ private: void fun1() const {cout ＜＜ 'fun1'; } protected: void fun2() eonst {cout ＜＜ 'fun2'; } public: void tim3() const { cout ＜＜ 'fun3'; }}; class Derived: protected Base{ public: void fun4() const {cout ＜＜ 'fun4'; }};int main(){Derived obj;obj.fun1();// ①obj.fun2();// ②obj.fun3();// ③obj.fun4();// ④return 0;}其中有语法错误的语句是( )。