1. We ate out at McDonald's. 2. We ate out at a McDonald's. 3. We ate out at the McDonald's. 4. We ate out at McDonald's fast food shop 5. We ate out at a McDonald's fast food shop 6. We ate out at the McDonald's fast food shop
All are OK, including 4, depending on how many McDonald's there are to choose from in the immediate vicinity-- but no one would EVER say 4, 5 or 6: it would be difficult to find a greater modern redundancy.
These three forms will always be right if you use the proper name of a chain restaurant, and 'the' is not an intrinsic part of that name, Ms. Jandi.
(1) indicates that you chose that chain for your meal; (2) indicates that you chose an unspecified member of that chain; (3) indicates that you chose a specified (perhaps previously-mentioned or commonly-known) member of the chain.
Number 3 would be a lot better if you added a modifier. You may use either an adjective or noun.
We ate at the new Pizza Hut. We ate at the Pizza Hut on Times Street. We ate at the new Pizza Hut on Times Street.
Saying "We ate at the McDonald's." or "Let's have a frap at the Starbucks." sounds strange. Do away with the "the" unless that particular place has been
Thank you for your useful information! I'd like to ask you a question; help me again please! - Saying "We ate at the McDonald's." or "Let's have a frap at the Starbucks." sounds strange. Is it true? Don't we use 'the' in everyday expressions? Don't "The" and "McDonald's, Pizza Hut, Starbucks, etc without any modifier" come together? Please confirm this!
As Eric explained, and as you know, 'the' indicates a specific noun, or a noun previously referred to, or a noun whose identity is known by both speaker and listener. 'We ate at the McDonald's' or 'Let's have a frap at the Starbucks' sounds strange only out of context. The context might be:
'Where did you have lunch?' 'We ate at the McDonald's in the mall.' (specificity--to differ