7-3 Present Perfect & Past Simple

I finished my aircraft walk-around an hour ago. Have you finished yours yet?

Finished Actions: Past or Present?

As discussed in Grammar 7-1, the Present Perfect always connects the past with the present. There is always information about the present in a Present Perfect sentence:

We can't depart. The runway hasn't opened yet.
- Present = The runway is closed.
I've worked in this centre for many years.
- Present = I work in this centre now.
The radar been down since the afternoon.
- Present = The radar is still down.
He can't go skydiving with us. He's broken his leg.
- Present = He is unfit to go skydiving with us.

We use the Present Perfect if the time of the finished action is not important or unknown. If we want to describe the specific time when the action happened, use the Past Simple tense:

Present Perfect	Past Simple
I've taken a break.	I took a break an hour ago.
I've been to Air Traffic Control Centre twice.	I went to Air Traffic Control Centre last year and in 2006.
The sun has set.	The sun set five minutes ago.
He's already gone to the Control Tower.	He went to the Control Tower at 2200.

It is common to use the Present Perfect when describing actions that have happened during a time period that is unfinished. This period continues now:

BAW247 has called a couple of times today.

Since yesterday, my aviation blog has gotten over 20,000 visits.

I haven't been to the lake yet this summer.

Details of Experiences

As studied in Grammar 7-1, we use the Present Perfect to talk about our experiences:

I've already seen that Singapore A380.
CG-NDI has landed here before.
He's tried aerobatics.

However, we use the Present Perfect only to introduce our experiences. English speakers usually use the Past Simple tense to give more information or describe the details of the experiences:

I've already seen that radar playback. Leslie and I went to see it last Tuesday.
She's met me before. We met at the flight school last year.
He's tried flying aerobatics. He did it while he was on vacation in California a couple of years ago.

Duration: Past or Present?

We use the Present Perfect to describe the duration of unfinished situations and actions with since and for:

It's been raining since last night.

I've worked with Shaun for six or seven years.

We've been sitting here and talking weather for an hour.

She's had this problem since she was new.

Use the Past Simple to describe the duration of something that is finished:

I flew on that aircraft for many years.
- I don't fly on it anymore.
The pilots worked together for about ten years.
- They don't work together anymore.
He was my trainee for only six months.
- He is not my trainee anymore.

Do not use since if the action is finished. Since always means the action or situation continues now:

I worked with her on arrival ~~since~~ from 1700 to 1830.
I flew last night ~~since~~ from 2300 until 0600.

Duration of Unfinished Actions & Situations

As we've studied, English speakers often describe the duration of unfinished actions and situations with the Present Perfect tense. It is possible however to describe this duration another way.

Sometimes, instead of using the Present Perfect to describe how long something has continued, we choose the Past Simple to describe when the action or situation started.

Notice that the Present Perfect and Past Simple sentences have largely the same meaning but use different verbs and time expressions:

Present Perfect	Past Simple
I've known her for five years.	I met her five years ago.
I've been in Canada since February.	I came to Canada in February.
It has been raining for a couple of hours.	It started raining a couple of hours ago.
He's had his computer since he was in university.	He got his computer when he was in university.

In questions about unfinished actions or situations, how long is used with the Present Perfect, and when is used with the Past Simple:

How Long...?	When...?
How long have you known her?	When did you meet her?
How long have you been in Canada?	When did you come to Canada?
How long has it been raining?	When did it start raining?
How long has he had his computer?	When did he get his computer?

Exercise

Open the exercise to begin the activity. Follow the instructions in the document.

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