CREATE TABLE "250cc_classification" (
  "rider" text,
  "manufacturer" text,
  "laps" real,
  "time" text,
  "grid" real
);

Question: Which rider has time of +19.751?
SQL: SELECT "rider" FROM "250cc_classification" WHERE "time"='+19.751';

Question: Which manufacturer of aprilia wth time of +1:36.557 has the highest lap?
SQL: SELECT MAX("laps") FROM "250cc_classification" WHERE "manufacturer"='aprilia' AND "time"='+1:36.557';

Question: What is time of manufacturer with grid 21?
SQL: SELECT "time" FROM "250cc_classification" WHERE "grid"=21;

Question: What is the total of laps with grid of 2
SQL: SELECT SUM("laps") FROM "250cc_classification" WHERE "grid"=2;

Question: What is the lowest grid with time of +0.499,when laps are larger than 21?
SQL: SELECT MIN("grid") FROM "250cc_classification" WHERE "time"='+0.499' AND "laps">21;

Question: What is the total laps when manufacturer of gilera has time of 40:19.910 and grid is larger than 3?
SQL: SELECT SUM("laps") FROM "250cc_classification" WHERE "manufacturer"='gilera' AND "time"='40:19.910' AND "grid">3;