Answer:
After filling in the blanks with an article, the sentence is:
Once upon a time, there lived a one-eyed monster in a castle.
Step-by-step explanation:
In English, we have one definite article "the", and two indefinite articles, "a" and "an". "The" is only used when we speak of something specific. "A" or "an" is used to talk about something in general or something that is being introduced (mentioned for the first time). Take a look at the sentence below:
- I saw a girl running the other day. The girl had beautiful brown hair. → The first sentence is introducing the girl, which is why it uses the indefinite article "a". The second sentence is talking about that same girl, a specific person, which is why it uses "the".
The only difference between "a" and "and" is that "a" is used before consonant sounds, while "an" is used before vowel sounds. Example: a fox - an ant.
"Once upon a time" is a fixed expression since it never changes. We cannot say "once upon the time".
We use "a" before "one" because its first sound is consonant-like (/w/).
We say "a castle" because we are mentioning the castle for the first time.