Ago

Ago is an adverb of time. It measures the time from "now" back to a fixed point.
For Example: Sam was born 34 years ago. (= 34 years before "now")

subject	verb in the past tense	length of time phrase	ago
Sam	was born	34 years	ago

Ago can follow many different length of time phrases. For examples:
1. She got married a loing time ago.
2. They lost their dog a day ago.
3. The farmers started work ages ago.

Note:
A. Question form: How long ago did you leave your house?

B. The time phrase + ago can come first. For example: A few days ago, they were complaining about the service.

C. Do not use ago whit the Present Perfect. For example: The exam results have been declared many days ago.

I hope this article helps. If you have any question, please leave a comment below.