Use "the" before the noun that is known for both you and your audience When you say "we live in the city" audience knows what city you're talking about

English has two articles: the and a/an. The is used to refer to specific or particular nouns; a/an is used to modify non-specific or non-particular nouns. We call the the definite article and a/an the indefinite article. the = definite article a/an = indefinite article For example, if I say, "Let's read the book," I mean a specific book. If I say, "Let's read a book," I mean any book rather than a specific book. Here's another way to explain it: The is used to refer to a specific or particular member of a group. For example, "I just saw the most popular movie of the year." There are many movies, but only one particular movie is the most popular. Therefore, we use the. "A/an" is used to refer to a non-specific or non-particular member of the group. For example, "I would like to go see a movie." Here, we're not talking about a specific movie. We're talking about any movie. There are many movies, and I want to see any movie. I don't have a specific one in mind. For more tips, go to: http://www.italki.com/knowledge/Contribution.htm?n=ENGLISH%20GRAMMAR

1. We live in a city. 2. We live in a flat. 3. A fish lives in the sea, and a bird lives on a tree. 4. A lemon is yellow, and a tomato is red. 5. What color is the lemon? 6. What color is the sky? What color is the snow? 7. The sky is blue, and the snow is white.

But I see a lamp on the table.

Good question.