Answer:
The convict tried to plead with the guards, but he shouted at them and ended by threatening them.
Explanation:
Parallelism occurs when a text contains the same grammatical structure. In the example given, the three sentences are written in the Past Simple tense and indicate a series of finished actions in the past. As a consequence, they can be combined by adding the coordinating conjunction but to introduce a contrast, using pronouns to avoid repetition, and leaving the three main verbs in the Past Simple tense: tried, shouted and ended.
