What are examples of sentences using indefinite article to introduce nouns for the first time?

Then for each of these sentences, could you help me write a second sentence using the definite article to continue talking about those nouns?

1 Answer
Jan 6, 2017

Answer:

See explanation.

Explanation:

An example can be:

For lunch I had a sandwich and an apple. The sandwich was not very good.

Here sandwich and apple were introduced for the first time in the first sentence, so the indefinite article a/an was used.

The second sentence spoke about the known object (the sandwich mentioned before) so it used the definite article the