TASK DEFINITION: In this task you are given a sentence with one coordinating conjunction (for, and, nor, but, or, yet, and so). You must judge whether the order of two coordinated clausal conjoints have been inverted or not. Inversion would result in the sentence sounding unnatural. Label the instances as "Original" or "Inversion" based on your judgment.
PROBLEM: She looked at him , but he did not say anything .

SOLUTION: Original

PROBLEM: They 're not in order , but all the pieces are there .

SOLUTION: Inversion

PROBLEM: His voice softened , but he still had a guarded look on his face .

SOLUTION:
Inversion