Table: how_its_made_episodes_18
Columns: series_ep
episode
segment_a
segment_b
segment_c
segment_d

Question: Which items in segment A have a segment D of marble sculptures?
SQL: SELECT "segment_a" FROM how_its_made_episodes_18 WHERE "segment_d" = 'marble sculptures'

Question: Which segment A also has a segment D of kitchen shears?
SQL: SELECT "segment_a" FROM how_its_made_episodes_18 WHERE "segment_d" = 'kitchen shears'

Question: Which items in segment C is episode 160?
SQL: SELECT "segment_c" FROM how_its_made_episodes_18 WHERE "episode" = 160