Cnd cnd = Cnd.NEW();
            cnd.and("aaa","=","aaa");
Cnd cnd1 = cnd;
                cnd1.and("bbb","=","bbb");
Cnd cnd2 = cnd;
                cnd2.and("ccc", "=", "ccc");
Cnd cnd3 = cnd;
                cnd3.and("ddd", "=", "ddd");

Cnd也没有clone方法呀？这么一套走下来，怎么让cnd保持不改变？