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Complete the time traveler's mission log. Select ALL the options that grammatically and logically fit into the blank to describe the scene he found upon returning.
When Professor Higgins finally returned to the year 2024, his laboratory was a complete disaster. It was obvious that his robotic assistant ________
The correct answers are: had been trying to bake a cake, as flour covered every surface. had tried to bake a cake and completely destroyed the temporal oven. had dismantled the main console while he was away.
When describing the cause of visible results in a past narrative ("the laboratory was a disaster"), we use perfect tenses:
- Past Perfect Continuous ("had been trying") emphasizes the duration of an activity that caused a visible result in the past.
- Past Perfect Simple ("had tried", "had dismantled") focuses on the completion of the actions before the Professor returned.
The options with "was trying... covers" and "has been trying" improperly mix present tenses ("covers", "has been") into a strictly past-tense narrative ("returned", "was a disaster").