cooperated
v.v. worked together with someone else to achieve a common goal. You use this when people or groups help each other to finish a task.
v. past tense of 'cooperate'; refers to the act of working jointly toward the same end. Intransitive — describes the collaborative action of multiple parties.
The two departments cooperated to finish the report on time.
Local authorities and international agencies cooperated closely to distribute aid after the storm.
Although the rival firms were usually in direct competition, they cooperated on this specific initiative to establish industry-wide safety standards that benefited all consumers.
The verb is intransitive and typically takes the preposition 'with' for partners or 'on' for projects.
they cooperated the projectthey cooperated on the projectCooperate is intransitive and cannot take a direct object; it requires a preposition like 'on' or 'with'.