We _____________ our breakfast half an hour ago.
- finished (Simple Past)
- have finished (Present Perfect)
- had finished (Past Perfect)
I chose the "have finished", but the answer is "finished". Why?
"Finished" is correct because it is the Past Simple.
We use the Past Simple to speak about events that happened in the past.
"Have finished" isn't correct because it is the Present Perfect. An hour ago is in the past (a past time) and isn't connected to the present anyhow. If it were still happening it would be correct.
We do not use the present perfect with an adverbial which refers to past time which is finished.
It should be noted that point of time in the past indicates that action took place at a point in the past (definite point of time). The point of time is expressed by: since, ever since, last, yesterday, ago, back, etc.
1) She returned two days ago.
2) We finished breakfast half-hour ago.
The past perfect is usually used to indicate the ‘past in the past’. In other words, when we refer to two past activities we may put the one occurring first in the past perfect as in “When I reached the railway station, the train had left”