1.You should use present perfect or present perfect progressive
1. John looks tied, we think he ( do) his homework.
2. Their university ( study) ecological problems for many years.
3. A lot of trees are lying on the ground. It seems to me a very strong wind ( blow)
4. I’m very sorry that I (break) your cup.
5. He (know) us for many years
2.Find out the time of these sentences present perfect or present perfect progressive
1. It has been raining all day. When will it stop?
2. It is noon. You have been working on the computer for two hours already
3. We have never been to Australia. And John has been living there all his life.
4. She says she has never spoken to any famous traveller.
5. Nancy has travelled in Canada this year.