Table: mex_grand_prix_1968
Columns: driver
constructor
laps
time_retired
grid

Question: Which constructor was there for the race with 25 laps?
SQL: SELECT "constructor" FROM mex_grand_prix_1968 WHERE "laps" = 25

Question: Which driver had brm as a constructor and a time/retired of engine?
SQL: SELECT "driver" FROM mex_grand_prix_1968 WHERE "constructor" = 'brm' AND "time_retired" = 'engine'