How to get rid of smoke smell<br>Let the book air out. Gently hang an open book over a railing or on a clothesline outside for a few hours to a day. This should cause the smell to decrease.
The smoke smell in books will naturally dissipate even if you don't hang them on clotheslines.
The passage makes no mention of what will happen to the smoke smell in books if this procedure isn't done.  This statement can't be known either way based on the passage.  I think the system got it wrong because it limits its thinking to what is presented  explicitly in the passage, which only talks about hanging books to reduce their odor.
( z1 dissipate :ARG1 ( z2 smell :ARG1 ( z3 smoke ) :location ( z4 book ) ) :ARG1-of ( z5 natural ) :concession ( z6 even-if :op ( z7 hang :polarity - :ARG0 ( z8 you ) :ARG1 z4 :ARG2 ( z9 clothesline ) ) ) )