The present perfect and the present perfect continuous :

A/

§ We use the present perfect continuous  rather than present perfect simple when we draw a conclusion from what we can see and hear, ect. This form is usually used to complain and criticise.

Ex:

-You have been working all night. You look exhausted.

- Someone has been messing around with my computer.

B/

§When we talk about the result of circumstances or an activity, we use the present perfect rather than the present perfect continuous. When the focus is on the process we use either the present perfect or the present perfect continuous .

Ex:

- The prices of houses have increased by 10%.(The focus is on the result)

- The prices of houses have been increasing recently. (or “have increased”-The focus is on the process-)

C/

§ The present perfect continuous emphasises that an activity is ongoing or repeated.

Ex:

-She has been reading the book all day.

§The present perfect suggests that an activity happened only once or on a specified number of occasions

-Sam has represented the company at 35 forums so far.