Table: approach_landing_tests
Columns: test_flight
date
speed
altitude
crew
duration
comment

Question: What is Duration, when Test Flight is Taxi Test #2?
SQL: SELECT "duration" FROM approach_landing_tests WHERE "test_flight" = 'taxi test #2'

Question: What it Duration, when Test Flight is Free Flight #3?
SQL: SELECT "duration" FROM approach_landing_tests WHERE "test_flight" = 'free flight #3'

Question: What is Date, when Comment is Tailcone On, Lakebed Landing, and when Duration is 5min 34 s?
SQL: SELECT "date" FROM approach_landing_tests WHERE "comment" = 'tailcone on, lakebed landing' AND "duration" = '5min 34 s'

Question: What is Crew, when Date is July 26, 1977?
SQL: SELECT "crew" FROM approach_landing_tests WHERE "date" = 'july 26, 1977'