Past to Present
Present Perfect
Present Perfect to Express Past to Present
The present perfect connects an action or state which began in the past and to the present moment in time.
He has been waiting to reach the time fence for three weeks and now is enforcing the new policy.
I've communicated with three companies who want us to make on request.
They have been managing our time scheduling platform for three years
Positive Form:
Subject + have + past participle + (object(s))
He has been waiting to reach the time fence for three weeks and now is enforcing the new policy.
Negative Form:
Subject + have + not + past participle + (object(s))
Alan hasn't worked on flow production for long.
Question Form:
(Wh?) + have + subject + past participle + (object(s))
How long have you tried to label me?
Present Perfect to Express Duration
When an action begins in the past and continues into the present moment we use the present perfect. This use of the present perfect expresses duration over time FROM the past moment TO the present moment.
Example:
He has been waiting to reach the time fence for three weeks and now is enforcing the new policy.
I've communicated with three companies who want us to make on request.
They have been managing our time scheduling platform for three years
Contrast to the Present Simple
The use of the present simple expresses activities that occurs on a regular basis, such as habits and routines.
Example:
George doesn't drive the industrial truck on Mondays.
Jim usually drives the industrial truck on Wednesdays.
In contrast, the use of the present perfect expresses actions that take place over time beginning in the past and coming into the present moment in time.
Example:
He has been waiting to reach the time fence for three weeks and now is enforcing the new policy.
They have fought for our right to assemble for a hundred years.
Use of 'For', 'Since' and 'How long'
Use 'for' with the present perfect or present perfect continuous to indicate the duration of an activity or state.
They have been managing our time scheduling platform for three years
They have searched for a new floor manager for six months now.
Use 'since' with the present perfect or present perfect continuous to indicate a specific point in time an activity or state began.
Bob has failed to draw a plan that works since 1982.
The floor stock that is usually consumed in production has collected dust in the corner since July.
'How long' is used in questions to ask about the duration of an activity or state.
How long have you tried to label me?