Here are the sentences completed with the correct verb forms:
The boys have been fishing all afternoon. They have caught ten fish so far.
Let’s sit down. I’m tired. We have been dancing for hours.
Kelly is standing on the corner. She has been waiting for her boyfriend for the past 20 minutes.
There is a police car parked on the street across from my house.
I have been watching it for over an hour, but nothing has happened yet.
Please answer the phone. It has been ringing for the past five minutes.
Anna has been in the hospital for over a month. She may come home next week.