Table: bob_gerard_era
Columns: year
entrant
chassis
engine
points

Question: What year has an ERA engine and an ERA A-type chassis?
SQL: SELECT "year" FROM bob_gerard_era WHERE "engine" = 'era' AND "chassis" = 'era a-type'

Question: What is the earliest year that has a Bristol engine?
SQL: SELECT MIN("year") FROM bob_gerard_era WHERE "engine" = 'bristol'