Perfect and Perfect Progressive Tenses

Present Perfect
They have moved into a new apartment.
Have you ever visited Mexico?
I have never seen snow.
I have already seen that movie.
Jack hasn’t seen it yet.
Ann started a letter to her parents last week, but she still hasn’t finished it.
Alex feels bad. He has just heard some bad news.
Notice the examples: the adverbs ever, never, already, yet, still and just are frequently used with the present perfect.

Present Perfect
We have had four tests so far this semester.
I have written my wife a letter every other day for the last two weeks.
I have met many people since I came here in June.
I have flown on an airplane many times.
Notice so far is frequently used with the present perfect.

Present Perfect
I have been here since seven o’clock.
We have been here for two weeks.
I have had this same pair of shoes for three years.
I have liked cowboy movies ever since I was child.
I have known him for many years.
In the examples, notice the difference between since and for:
Since + a particular time
For + a duration of time

Present Perfect Progressive
I have been sitting here since 7 o’clock.
I have been sitting here for two hours.
You have been studying for five straight hours.
It has been raining all day.
I have known Alex since he was a child.
INCORRECT: I have been knowing Alex since he was a child.
Used with time words, such as: for, since, all morning, all day, all week.

Present Perfect Progressive
I have been thinking about changing my major.
All of the students have been studying hard.
My back hurts, so I have been sleeping on the floor lately.
I have lived here since 1995.
I have been living here since 1995.
He has worked at the same store for ten years.
He has been working at the same store for ten years.
A general activity in progress recently, lately.
With certain verbs (most notably live, work, teach), there is little or no between the two tenses when since or for is used.

Past Perfect
Sam had already left by the time Ann got there.
Someone had forgotten to lock the door.
Sam had already left when Ann got there.
Sam had left before Ann got there.
Sam left before Ann got there.
After the guests had left, I went to bed.
After the guests left, I went to bed.
The past perfect expresses an activity that was completed before another activity or time in the past.
If either before or after is used in the sentence, the past perfect is often not necessary because the time relationship is already clear. The past simple may be used.

Past Perfect Progressive
The police had been looking for the criminal for two years before they caught him.
Erich finally came at 6 o’clock. I had been waiting for him since four-thirty.
When Judy got home, her hair was still wet because she had been swimming.
I went to Jane’s house after the funeral. Her eyes were red because she had been crying.
The past perfect progressive emphasizes the duration of an activity that was in progress before another activity or time in the past.
This tense also may express an activity in progress close in time to another activity or time in the past.