UNIT 10. Present perfect continuous and simple (I have been doing and I have done)

A. Study these example situations:
Ann's clothes are covered in paint. She has been painting the ceiling.
Has been Painting is the present perfect

We are interested in the activity. It does not matter whether something has been finished or not. In this example, the activity (painting the ceiling) has not been finished.

The ceiling was white. Now it is blue. She has painted the ceiling.
Has painted is the present perfect simple.
Here, the important thing is that something has been finished. 'Has painted' is a completed action. We are interested in the result of the activity (the painted ceiling), not in the activity itself.

Compare these examples:
& My hands are very dirty. I've been repairing the car. The car is OK again now. I've repaired it.
& She's been smoking too much recently. She should smoke less. Somebody has smoked all my cigarettes. The packet is empty.
& It's nice to see you again. What have you been doing since we last met? Where's the book I gave you? What have you done with it?
& Where have you been? Have you been playing tennis? Have you ever played tennis?

B. We use the continuous to ask or say how long (for an activity that is still happening):
& How long have you been reading that book?
& Mary is still writing letters. She's been writing letters all day.
& They've been playing tennis since 2 o'clock.

We use the simple to ask or say how much, how many or how many times (completed actions):
& How many pages of that book have you read?
& Mary has written ten letters today.
& They've played tennis three times this week.

C. There are some verbs (for example, know/like/believe) that are normally not used in the continuous:
& I've known about it for a long time. (not 'I've been knowing')

For a list of these verbs, see Unit 4A.