| The present perfect progressive tense has severaldifferent uses. One is very similar to a common use
 of the "normal" present perfect tense: showing an
 action that began in the past and that is still continuing
 now. When the present perfect progressive is used
 in this way, the emphasis is on the length of the
 continuing activity. In addition, use of the present
 perfect progressive often suggests that the action
 has continued with no interruption from its beginning
 until the present.
 For this use of the present perfect progressive, the"time words" for and since are very commonly used:
 
			Joe has been studying at State Universitysince September.
 The baby has been crying for a long time.What's wrong?
 I've been driving since daybreak. I'll have tostop soon, I think.
 Other "time words" are also commonly used withpresent perfect progressive--in particular, all + a period
 of time:
 
			It's been snowing all day. When willit stop?
 She's been studying all morning. I'm sureshe'll take a break soon.
 I've been thinking about Bob all week.I really miss him!
 We've been trying to reach Sara all afternoon.Where could she be?
 To add even more emphasis to the idea that the actionhas been uninterrupted, the set phrase the entire ____
 is sometimes used:
 
			It's been snowing the entire day and there'sno end in sight.
 She's been studying the entire morning. She'llhave a headache if she doesn't take a break soon.
 I've been thinking about Bob the entire week.I hope everything's OK with him.
 We've been trying to reach Sara the entireafternoon. Are you sure she's at home?
  _______________________________________________
 Special Note:
 All of the example sentences above could also be writtenwith "normal" present perfect tense, but if they were, the
 feeling and emphasis would be quite different: there would
 be much less of a suggestion that the action was uninterrupted
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