a(1)=20: a(2)=3: a(3)=21: a(4)=37
a(5)=62: a(6)=20: a(7)=13: a(8)=33
k=Abs(a(2)-a(1))
For i=3 To 8
If Abs(a(i)- a(i-1))>k Then k= Abs(a(i)-a(i-1))
Next
执行该程序段后,变量k的值为( )