How many days were the station of Soyuz 35 in flight down were in orbit?
CREATE TABLE "station_crews" (
  "expedition" text,
  "crew" text,
  "launch_date" text,
  "flight_up" text,
  "landing_date" text,
  "flight_down" text,
  "duration_days" text
);
SELECT "duration_days" FROM "station_crews" WHERE "flight_down"='Soyuz 35';