6.3 present simple, present continuous, present perfect, present perfect continuous 1. This system is not / has not been used for several years, but we believe it is still valid today. 2. I am an assistant professor at the Department of Robotics where Ii bam working / have been working for the last two years. 3. Wei bbelieve / are believing that this is the first time that the problem is / has been addressed. 4. At the moment Ii bam working / have been working on anew project. 5. This is the first time we experience / have experienced a problem like this. 6. Don’t worry Ii bam / have been in the office since 8.0. 7. Fortunately we don’t have / haven’t had this problem fora while now. 8. How long are you / have you been here for – since last year or the year before 9. How long are you / have you been here for – till the end of this year or next 10. This is / has been the second time today that the computer crashes / has crashed . 1. has been 2. have been working 3. believe, has been 4. am working 5. have experienced 6. have been 7. haven’t had 8. have you been 9. are you 10. is, has crashed
