Have.
The term Poliice force is considered as plural, just like football teams.
Example - Arsenal have a new stadium.
Chelsea have to play in Europe next week.
In spite of our retirements, the police force still (has) enough power to fight against for justice.
HAS---IT'S BECAUSE THE WORD " FORCE" IS AN UNCOUTABLE NOUN.
2006-10-18 22:38:48 補充:
EXAMPLE : A U.N. peacekeeping force was sent to that country.一支聯合國維持和平部隊被派往該國。