cooperator

基本解釋

So long as you think of yourself alone, you cannot be a good cooperator.
如果總想著自己，你就不能成為一名好社員。
The foreign cooperator shall send a certain number of teachers from its own educational institution to teach in the Chinese-foreign cooperatively-run school.
外方合作辦學者應當從本教育機構中選派一定數量的教師到中外合作辦學機構任教。
Article 10 A Chinese or foreign cooperator in running a school may contribute with funds, in kind or in forms of land-use right, intellectual property rights or other assets to establish the school.
第十條中外合作辦學者可以用資金、實物、土地使用權、知識產權以及其他財產作為辦學投入。

Then there is the relationship between the cooperator and the person against whom they testify.
FORBES: Why do people have a negative view of cooperators?
The life of a government cooperator is not an easy one but it does have benefits when it comes to reducing prison time.
FORBES: Connect
In addition, you have the personal circumstance of the cooperator.
FORBES: Why do people have a negative view of cooperators?