We use the present perfect continuous for actions that started in the past and are still happening now . These actions are on going and are not finished . For questions about duration , we use how long ,
Lonnie Thompson has been trying to find information in glaciers .
How long has Paul Nicklen been working as a photojournalist?
We use the present perfect , not the present perfect continuous, in the following case
with repetition from the past to present
with an indefinite time in the past
with always and never
for duration with non action verbs
with questions about repetition , using how much or how many
Thompson has climbed many glaciers
Have you ever climbed a mountain ?
I have always wanted to climb a mountain, but i have never done it
Lonnie Thompson has been interested in glaciers
for many years
How many times has Thompson gone to Peru
How many time has he spent on glaciers ?
Compare :
(a) I have read some interesting articles
I have been reading a book about glaciers
I have climbed several mountains since 2010
My friend has been climbing a mountain in Alaska for the last three days.
He has worked as a photographer for many years.
( In some cases , there is no difference in meaning between the present perfect and the present continuous )
He has been working as a photographer for many years.
When he was in college, Lonnie Thompson studied geology.
He made his first glacier exploration in the 1970s
We use simple past for an action that was completely in the past . Often a definite time is mentioned
No comments:
Post a Comment