"A" vs. "The"
- I bought a new camera.
- I bought two new cameras.
- I bought an orange at the supermarket.
- I spent an hour watching television.
- After the noun has been introduced to the listener and is being referred to a second time. Example: I took a camera with me to the top of the mountain, but the camera didn't have batteries.
- With nouns of which there is only one. Example: I want to clean up the environment on the moon.
- With nouns which represent a larger institution or concept for a place. Examples: the post office, the hospital, the army, the park, the beach
- With many location names and in the names of countries which have a plural feeling. Examples: The United States, The Phillipines, The Mediterranean Sea, The Cayman Islands
- I ate at a restaurant in Shibuya. (First time being introduced, and the listener does not know which restaurant precisely)
- I at at the restaurant in Shibuya near your house. (First time introduced, but the listener likely knows exactly which restaurant this is.)
- I want a new phone. (Non-specific about what type of phone; listener does not know which model. Perhaps the speaker has not decided which model yet.)
- I want the new model of phone from Sony. (Specific, and the listener likely knows which model is being talked about.)