Choose the word(s) or phrase(s) which best fill(s) the gap.
I would have been surprised if you ____________ the orange.
Answer Details
The best word(s) or phrase(s) to fill the gap is "had plucked".
Explanation: The sentence is written in the past tense and has a hypothetical tone, indicating that the speaker was imagining a scenario in which the person in question plucked the orange. The use of "would have been surprised" implies that the scenario being discussed did not actually happen. To reflect the hypothetical and past-tense nature of the sentence, the past perfect tense "had plucked" is the most appropriate choice.