可能用到的数据：
z0.0228=2，
F0.025(25,16)=2.62，F0.025(24,15)=2.70，F0.025(16,25)=2.38，F0.025(15,24)=2.44，t0.025(39)=2.0227，t0.05(39)=1.6849，t0.025(41)=2.0195，t0.05(41)=1.6829 F0.025(3,14)=4.24，F0.05(3,14)=3.34，t0.025(5)=2.5706，t0.05(5)=2.015 t0.025(7)=2.3646，t0.05(7)=1.8946，F0.05(1,5)=6.61，