1. I thought the film was (a drag.) - Informal/spoken. In this context, "a drag" means something boring, uninteresting, or tedious.
2. Smoking isn't (permitted.) - Formal. It means not allowed or not allowed according to a certain set of rules or regulations.
3. It's a (scary) film. - Informal/spoken. "Scary" means something that causes fear or fright.
4. This watch cost fifty (quid.) - Informal/spoken. "Quid" is a slang term for the British pound sterling, so it means fifty pounds.
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