CREATE TABLE "skilift_system" (
  "name_or_route" text,
  "type" text,
  "elevation_groundstation" real,
  "elevation_mountainstation" real,
  "slope_length" real,
  "capacity_in_persons_hour" real,
  "construction_year_s" text
);

Question: Which elevation groundstation has a capacity in persons/hour larger than 820, and a Name or route of lager 1, and a slope length smaller than 336?
SQL: SELECT AVG("elevation_groundstation") FROM "skilift_system" WHERE "capacity_in_persons_hour">820 AND "name_or_route"='lager 1' AND "slope_length"<336;

Question: Which slope length has a type of surface lift, and an elevation groundstation smaller than 1974, and a construction year(s) of 1971, and a Name or route of alpmatten 1?
SQL: SELECT "slope_length" FROM "skilift_system" WHERE "type"='surface lift' AND "elevation_groundstation"<1974 AND "construction_year_s"='1971' AND "name_or_route"='alpmatten 1';