What number with the opponent Fokker D.vii have with a time of 1655?
CREATE TABLE "verified_aerial_victories" (
  "number" real,
  "time" real,
  "aircraft" text,
  "opponent" text,
  "location" text
);
SELECT SUM("number") FROM "verified_aerial_victories" WHERE "opponent"='fokker d.vii' AND "time"=1655;