Present perfect simple present perfect continuous

                          computer addiction     after the appearing computers,   especially internet, a  lifestyle has been changed enormously. they help us a lot. but there is a problem. more and more people are  becoming a computer addict all over the world. computer addiction is a new term which describes a dependency on one's computer. a computer addict plays computer games endlessly, or/and  sits on the internet a lot.  everyone knows it's not good.

My  room is very light and large. there is a sofa on the right.next to the sofa there is a yellow nightstand. you can see a vase with flowers on my dresser. on the left side of the dresser there is a window. and next to the window there is my desk where i do my homework. of course,  i have a computer desk with my new net-book which connected to internet. along the long wall of my room there is a book-case with many shelves for books and cd-disks. there are some posters with my favorite pop-singers on the walls. and in the middle of the room there is a colorful carpet.  i love my room!