大家帮忙看看Fortran中这个错误是什么?怎么改?

大家帮忙看看Fortran中这个错误是什么?怎么改?
open(1,file='data.txt')
x09real h,v,a,t,f,v0,g,H0
x09f=0.03
x09t=0.1
x09g=9.8
x09H0=100
x09a=g
x09h=0
x09v=0
x09v0=sqrt(g/f)
x09do while(hv0)then
x09write(*,"(1x,F3.4)") v0
x09else
x09write(*,"(1x,F3.4)") v
x09end if
x09end do
x09end
x09
错误如下
F:fortran huiText1.for(2) : Error: A specification statement cannot appear in the executable section.
real h,v,a,t,f,v0,g,H0
--------^
Error executing df.exe.