Present Perfect Simple or Present Perfect Continuous.1. A pair of robins

1. A pair of robins has been building a nest in the porch since last week. I've been watching them from my window since they began.
2. They have pulled down most of the houses in this street, but they have not touched the old shop at the corner yet.
3. It was lovely at 11 o'clock, but since then the sky has been getting steadily darker and the wind has been rising. I'm afraid the fine spell has come to an end.
4. Custumers have been ringing up all morning complaining about getting incorrect bills. I know, something has gone wrong with our computer. The mechanic has been working on it since 9:30 a. m. I hope he has already found out of the housе for a week(наверное, эта часть другого предложения)
6. She has just sold two of her own paintings. She's lucky. I have been painting for 5 years and I haven't sold a single yet.
7. What have you done with my typewritter? I can't find it anywhere. Tom has just gone off with it. He says he'll bring it back when he has finished.
8. Mrs Brown has been living next door for quite a long time now but she has never said more than "Good morning" to me.