FORM Present Perfect Continuous
[HAS / HAVE] + [BEEN] + [VERB+ing]
EXAMPLES:
I have been waiting here for two hours.
She has only been studying English for two years.
NOTE: When you are using a verb tense with more than one part such as Present Perfect Continuous (has been studying), adverbs often come between the first part and the second part (has only been studying).
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USE 1 Duration from the Past Until Now
We use the Present Perfect Continuous to show that something started in the past and has continued up until now. "For five minutes", "for two weeks", and "since Tuesday" are all durations which can be used with the Present Perfect Continuous.
EXAMPLES:
They have been talking for the last hour.
She has been working at that company for three years.
James has been teaching at the University since June.
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USE 2 Recently, Lately
You can use the Present Perfect Continuous WITHOUT a duration such as "for five minutes", "for two weeks", and "since Tuesday". Without the durations, the this tense gives a more general meaning of "lately". We often use the words "lately" or "recently" in the sentence to strengthen this meaning.
EXAMPLES:
Recently, I have been feeling really tired.
She has been watching too much television lately.
Mary has been feeling a little depressed.
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IMPORTANT
Remember that the Present Perfect Continuous has the meaning of "lately" or "recently.";; If you use the Present Perfect Continuous in a question such as "Have you been feeling alright?", it suggests that the person looks sick or unhealthy. A question such as "Have you been smoking?" suggests that you can smell the smoke on the person. Using this tense in a question suggests you can see, smell, hear, or feel the results of the action. It is possible to insult someone by using this tense incorrectly.
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FORM Present Perfect
[HAS / HAVE] + [past participle]
EXAMPLES:
I have seen that movie many times.
I have never seen that movie.
NOTE: When you are using a verb tense with more than one part such as Present Perfect (have seen), adverbs usually come between the first part and the second part (have never seen).
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USE 1 Unspecified Time Before Now
We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with time expressions such as "yesterday," "one year ago," "last week," "when I was a chlid," "when I lived in Japan," "at that moment," "that day" or "one day." We CAN use the Present Perfect with expressions like "ever," "never," "once," "many times," "several times," "before," "so far," "already" and "yet."
EXAMPLES:
I have seen that movie twenty times.
I think I have met him once before.
There have been many earthquakes in California.
Has there ever been a war in the United States?
Yes, there has been a war in the United States.
People have traveled to the moon.
Form yahoo知識
http://hk.knowledge.yahoo.com/question/?qid=7006072402230
