Ago is used with a past tense and a time expression to count back from the present.

His father died three years ago.

He left ten minutes ago.

Before is used with a past perfect tense to count back from a past moment. Before can also be used to mean ‘at any time before now / then’. With this meaning, it can be used with both present and past perfect tenses.

I have seen her before.

Complete the following sentences using ago or before.

1. It happened a long time …………………………………..

2. Julie phoned ten minutes …………………………………………

3. We have been living in this city since about ten years ………………………………………..

4. I met Stella in Australia three years ………………………………………

5. When we got talking, I remembered that I had been at school with her 15 years …………………………………

6. I have seen this film …………………………………….

7. Have you been here ……………………………………..?

Answers

1. It happened a long time ago.

2. Julie phoned ten minutes ago.

3. We have been living in this city since about ten years ago.

4. I met Stella in Australia three years ago.

5. When we got talking, I remembered that I had been at school with her 15 years before.

6. I have seen this film before.

7. Have you been here before?