下面程序结果为：(     )

class Tree {
    private static String tree = "tree ";
    String getTree() {
        return tree;
    }
}
class Elm extends Tree {
    private static String tree = "elm ";
    public static void main(String[] args) {
        new Elm().go(new Tree());
    }
    void go(Tree t) {
        String s = t.getTree() + Elm.tree + tree + (new Elm().getTree());
        System.out.println(s);
    }
}