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Python 2, 54 52 bytes

-2 bytes thanks to xnor


k='unknowns'
for i in 8,6,2,0:print k[i/3:7],k[i%3:]


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The results from the / and % will be [[2, 2], [2, 0], [0, 2], [0, 0]] that will be the starting indexes, removing the un when 2, keeping the string unaltered when 0