许多教师属于专业工会，以改善工作条件。

Many teachers belong to a professional ___union to improve their working conditions.

美国公民自由联盟在保护个人自由方面起着关键作用。

The American Civil Liberties ___Union plays a key role in protecting individual freedoms.

他作为代表积极参与了学生会。

He was actively involved in the school student ___union as a representative.