The Case:
Lord Blackwood was found dead in his study on a cold, rainy Sunday afternoon. The detective on duty questioned three people who were in the house at the time. Each of them has an alibi. But one of them is lying.
The Suspects:
1.The Butler: "I was downstairs in the wine cellar choosing a bottle of Cabernet for dinner."
2.The Chef: "I was in the kitchen preparing the roast beef. It takes hours to cook."
3.The Maid: "I was at the front door collecting the post (letters) that the mailman had just delivered."
Your Mission:
Who is the killer and what was their mistake?
(Hint: To solve this, you need to think about daily life details in English-speaking countries).
Why are we doing this?
In English, just like in a good detective story, details matter. One wrong word, tense, or cultural misunderstanding can blow your cover.

