The document summarizes the present perfect tense in English. It is formed using "has/have" plus the past participle of the main verb. The present perfect is used to talk about unfinished past actions or states that continue to the present. It can be used with time expressions like "since" and "for" to indicate duration up to the present. It is also used to talk about actions that happened at an unspecified time before now. Examples are provided to illustrate its use.

1. Present prefect basic use

2. Present Perfect
FORM:
has/have + past participle
EXAMPLE: The verb “thrown” in “the ball has
Been thrown ” is past participle.

3. We use this tense when we want to talk
about unfinished actions that started in the
past and continue to the present. Usually we
use it to say ‘how long’ an action or state has
continued with ‘since’ and ‘for’. Often, we use
stative verbs in this situation:
.
I’ve known Kitty since 1994.
She’s lived in London for three years.

4. 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 SPECIFIC TIME EXPRESSIONS SUCH
AS: YESTERDAY, ONE YEAR AGO, LAST WEEK, WHEN I WAS A
CHILD, WHEN I LIVED IN JAPAN, AT THAT MOMENT, THAT
DAY, ONE DAY, ETC. WE CAN USE THE PRESENT PERFECT
WITH UNSPECIFIC EXPRESSIONS SUCH AS: EVER, NEVER,
ONCE, MANY TIMES, SEVERAL TIMES, BEFORE, SO FAR,
ALREADY, YET, ETC.

5. Duration From the Past Until
Now (Non-Continuous Verbs)
With Non-Continuous Verbs and non-continuous uses of Mixed
Verbs, we use the Present Perfect 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.

6. Example
Many people are surprised to learn that researchers have
discovered a single treatment that has many benefits.(reading
book P24 L1)
2 Both psychologists and psychiatrists have maintained for years
that Americans have overlooked one of the most significant public
health problems-chronic sleep deprivation.
(reading book P24 L13)
3 Other gimmicks have found their appeal more shortlived.(reading book P35 L11)
4 Has Google reached its peak?(reading book P116 L165)
5 Google’s earnings have continued to rise.(reading book P116
L168)
6 Has Google already captured so much of the Internet search and
advertising market that it will now have to expand into areas
where Google’s brilliant team has less expertise?(P116 L178)
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