Question

the train before I reached at the station (go)​

Answer 1

Before the train go i reached at the station

Answer 2

Explanation:

The train had left before we reached the station. We always write past participle form of verb when something has already happened in the first case. In this case the train had already left. We always use simple past tense form when something happens in the second part. In this case we reached the station.