My classmates _______ the text while I _______ the exercise.

The correct answer is: were reading / was doing Explanation: The sentence uses the Past Continuous tense to describe simultaneous actions happening in the past. "My classmates were reading the text" describes an ongoing action in the past, and "while I was doing the exercise" describes another ongoing action happening at the same time. Therefore, the first option, "were reading / was doing", is the correct one.