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I'm not questioning about 'Present Perfect VS Present Perfect Progressive'.

Please, let me know the difference of 'Present Progressive and Present Perfect Progressive'.

For example,

She is eating dinner for one hour. / She has been eating dinner for one hour.

It is raining outside. / It has been raining outside.

What are you talking about? / What have you been talking about?

He is watching TV all day. / He has been watching TV all day.

What is the difference of the meaning of each sentence?

Please, help me!
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She is eating dinner for one hour. / She has been eating dinner for one hour.
He is watching TV all day. / He has been watching TV all day.

It is raining outside. / It has been raining outside.

What are you talking about? / What have you been talking about?

You can't specify a period of time (as shown above in red) with the present progressive. You can with the present perfect progressive. So two of your eight examples are incorrect grammatically.

Other than that, the difference is the time at which the action occurs.
The present progressive says the action is occurring at the time you say the sentence. For example, suppose it is now 6 o'clock, and you say:

She is eating dinner. (Now, as I speak, at 6 o'clock, I see that she is eating dinner.)

It is raining. (Now, as I speak, at 6 o'clock, I see that it is raining.)

The present perfect progressive says the action started happening before the time you say the sentence and continues up to the time of your saying it. Maybe the action stops just before you say the sentence and maybe the action continues as you say the sentence, or even continues after you say the sentence, but the main idea is that it starts before you say the sentence. Again, suppose it is 6 o'clock.

He has been watching TV. (Now, as I speak, at 6 o'clock, I see that he has been watching TV from 3 o'clock until now. - or from 1 o'clock until now - or from 2:30 until now. -- The amount of time is not specified.)

He has been watching TV for two hours. ( Now, as I speak, at 6 o'clock, I see that he has been watching TV from 4 o'clock until now. -- The amount of time is specified in this case.)

It has been raining. (Now, as I speak, at 6 o'clock, I see that it has been raining from 3 o'clock until now. - or from 1 o'clock until now - or from 2:30 until now. -- The amount of time is not specified.)

It has been raining for a half hour. ( Now, as I speak, at 6 o'clock, I see that it has been raining from 5:30 until now. -- The amount of time is specified in this case.)

What have you been talking about? (Now, as I ask, at 6 o'clock, I ask the topic(s) of conversation during previous time up to the moment I ask.)
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Another way the present perfect progressive can work, if no amount of time is specified, is that the action occurred in the past and continued for some time and then stopped, but there is evidence at the time of speaking that the action did occur.
It has been raining, but it is not raining now. (I know because I can see now that the streets are wet.)
The children have been playing ball in the family room, but they are not playing ball there now. (I know because the ball is there, and it should be in the garage. I know because there is a mark on the wall where the ball probably hit the wall. I know because I can see the lamp overturned and broken on the floor.)
This last pattern often occurs with must to show that the speaker has reached a logical conclusion from the evidence before him.

It must have been raining, because the streets are wet.
The children must have been playing ball in the family room, because the lamp is broken.
CJ
Comments  
Students: Are you brave enough to let our tutors analyse your pronunciation?
She is eating dinner for one hour. / She has been eating dinner for one hour.

He is watching TV all day. / He has been watching TV all day.

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Actually, these two cases are the point that I eagar to know.

So, let me give you another example, if you don't mind. :-)

How is your vacation going so far? / How has your vacation been going so far?

You may say that we can't use the expression 'so far' with present progressive tense.

However, people are using that kind of tense forms now. (You can see them in the Google site right now.)

Thank you in advance. ;-)
Hi,

It is very simple. In the present perfect progressive you know the point of origin whereas the present progressive you don't know the point of origin. I have been eating for two hours vs. I am eating. Even if you omit the two hours it is understood that you knew when the action started.