Happening up to This Moment
Present Perfect Continuous
The present perfect continuous places the emphasis on the duration of a current activity. It is used to express either when an action in progress began, or the length of an action in progress. The present perfect continuous is never used with stative verbs.
Example:
I've been looking for the easter egg on this DVD menu screen for six hours. That's why my eyes are bloodshot.
How long have the programmers been discussing the perks of virtual memory?
She hasn't been working with the drop down menu all morning.
Positive Form:
Subject + have + been + 'ing' form of verb + (object(s)) + since / for + time expression
I've been reducing the verbiage in our manual since ten this morning.
Negative Form:
Subject + have + not + been + 'ing' form of verb + (object(s)) + since / for + time expression
She hasn't been working with the drop down menu all morning.
Question Form:
(Question Word) + have + subject + been + 'ing' form of verb?
How long have you been using a dual boot system?
Examples of What Caused Something
The present perfect continuous is often used to express the action that caused a present result.
Example:
I've been looking for the easter egg on this DVD menu screen for six hours. That's why my eyes are bloodshot.
I've been searching for a new email-client since Monday. That's why I'm sticking with outlook after all.
Present Perfect Contrasted with Present Perfect Continuous
The present perfect and present perfect continuous are both used to express the duration of an activity that begins in the past and continues into the present. Either form is used with general activities, although the use of the present perfect continuous can indicate that an activity is about to change. The present perfect continuous describes the duration of a current activity and tends to be used with more specific action verbs.
Example of Present Perfect:
Alan hasn't worked with trialware for very long.
I've tweeted three links.
Example of Present Perfect Continuous:
I've been updating my wordpress widgets since eight am. That's why my website has so many features.
I've been perusing free computer wallpaper since eight this morning. That's why nothing has been done!
When emphasizing the duration of the current action, use the present perfect continuous.
Example:
They've been designing the voice recognition software for two years.
They've been worrying about the virus for two days.
The present perfect continuous conveys the length of an activity, whereas the present perfect can also be used to relate the quantity, or amount finished up to the present moment in time.
Example:
I've developed three new distribution models.
I've used up three quarters of the hard disk space since I started podcasting last year.