clear
a=3
b=a
?"孪生素数对："
for i=3 to 100 step 2
    x=0
    for j=2 to i-1
        if i/j=int(i/j)
           x=1
        endif
    endfor 
    if x=0
       a=i
       if a-b=2
           ?b,a
       endif
       b=a
    endif
endfor