Here are the completed sentences with the adjectives in comparative or superlative form:
A: Did you know the Tuareg drink 7 cups of tea per day? B: Why not? There's nothing more refreshing than refreshing tea.
A: This is really tragic news. B: I know. It's the saddest thing I've heard in a long while.
A: Are you taking your luggage on the plane? B: No, it's heavier than 12 kilos; I'll have to check it in.
A: Keith was badly hurt in the accident. B: Yes, his condition is worse than I thought.
A: The Fords' house looks a mess. B: True. It's the most neglected house on our street.
A: Would you consider becoming a freegan? B: No, it's the strangest idea I've ever heard!
A: Did you enjoy your trip to Ellis Island? B: Actually, it was better than I had expected.