Which way is the right way?

[Rosko1234]

Which sounds better?

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

or is it:

2. 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.

[Torsten]

Hi,

I would say they have been building the nest since last Friday (point in time) or 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.
Regards
Torsten

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