Which way is the right way?

Which sounds better?

  1. A pair of robbins has built a nest in the porch since last week.

or is it:

  1. A pair of robins has been building a nest in the porch since last week.

In my opinion 2. sounds better. It tells us that the building process has been going on for a week and is still in progress.

One of my students thinks that 1. is also correct. She uses the example of: I have known her since I was young.
I accept her example and it sounds right to me. However, “I have known her since last week” does sound right.

Why am I confused about this? Please help me out.

And one more note, if you think that both are correct could you tell me what meaning does each imply. Thank you.


I would say they have been building the nest since last Friday (point in time) or [color=cyan]for one week (period of time) is better.

They have built the nest for one week (or since last Friday) might be grammatically OK but building is a process so present perfect continuous is much better here.

I have known her for one year is correct because it describes a state rather than an activity. You can know somebody ‘passively’ but you have to be active to build a nest or a house.

Please, let me know if you have any further questions.

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