Put the verbs in brackets into the present indefinite present continuous present perfect or present perfect continuois

Helen learns English at the institute.

She has been learning English since last summer.

They are busy now. They are discussing an important question. They have been discussing it since 5 o\'clock.

Where is Peter? - He is working in the library. - Has he been working long? - Yes, he has been working there for ten days.

He teaches French. He is a very experienced teacher. He has been teaching French for fifteen years.

I know Peter well. - Since when have you known him? I have known him since 1940.