出几道题，看看能答对多少

    下面3个命题，哪个（些）是永假命题(永远返回false)：

        bool QuestionAboutDouble(double x, double y)
        {
            return x.Equals(y) && x != y;
        }

        bool QuestionAboutType(int[] x)
        {
            if (x == null)
                return false;
            return x.GetType() != typeof(int[]);
        }

        bool QuestionAboutInt(int x)
        {
            for (int i = 0; i < 100; i++)
                x = x + x;
            return x < 0;
        }

    下面一道题的返回值是多少：

        int QuestionAboutClosure()
        {
            int x = 0;
            Func<int>[] funcs = new Func<int>[10];
            for (int i = 0; i < 10; i++)
                funcs[i] = () => x += i;
            (from f in funcs select f()).Count();
            return x;
        }