が公園で遊んでいた

… was playing in the park

→ が

phrase Rare #45,708

… was playing in the park A sentence fragment: が marks the subject, which comes before the term. 遊んでいた describes an ongoing action in the past; the English subject may be plural depending on context.

JA: 子供たちが公園で遊んでいた。

EN: The children were playing in the park.

たくさんの子供達が公園で遊んでいた。

Many children were playing in the park.

子供たちの一団が公園で遊んでいた。

A group of children was playing in the park.

子供たちが公園で遊んでいた。

The children were playing in the park.