"What was he doing?" is the past tense form in Engpsh.

The past tense is used to describe actions or events that have already happened. It is formed by adding "-ed" to regular verbs or by using the second form of irregular verbs.

Example sentences in Engpsh:

I saw him playing basketball yesterday.
He was working late last night.

Example translations in Chinese:

昨天我看见他在打篮球。
昨晚他工作到很晚。