2.给出下列各数:①4;②$\sqrt{4}$;③$\sqrt{40}$;④$\sqrt{40}$+1.其中,二次根式有( )
0 309701 309709 309715 309719 309725 309727 309731 309737 309739 309745 309751 309755 309757 309761 309767 309769 309775 309779 309781 309785 309787 309791 309793 309795 309796 309797 309799 309800 309801 309803 309805 309809 309811 309815 309817 309821 309827 309829 309835 309839 309841 309845 309851 309857 309859 309865 309869 309871 309877 309881 309887 309895 366461
| A. | 1个 | B. | 2个 | C. | 3个 | D. | 4个 |