Table: last_chance_learners
Columns: col
air_date
challenge
winner
test_taker
passed

Question: Who took test #4?
SQL: SELECT "test_taker" FROM last_chance_learners WHERE "col" = 4

Question: What episode aired on 18 April 2007?
SQL: SELECT MIN("col") FROM last_chance_learners WHERE "air_date" = '18 April 2007'

Question: Who had the challenge of night driving?
SQL: SELECT "test_taker" FROM last_chance_learners WHERE "challenge" = 'Night Driving'