Choose the correct alternative to complete the text. Olafur Nielson 1has designed/has been designing musical instruments since he was a child. In fact, in the last ten years he 2has built/has been building more than twenty different drum machines. But his most recent devices aren’t just any kind of musical instrument. Nielson 3has worked/has been working alongside researchers to develop instruments which can be played using thought, instead of hands and feet. Cognitive scientists 4have known/have been knowing for several years that the electric impulses created by thoughts can be used to express simple sounds and communicate ideas, but what Nielson 5has just developed/has just been developed goes beyond that. Using open source technology, Nielson 6has completed/been completing a prototype of a keyboard which can be played when connected to sensors on the musician’s head. According to initial reports, what Nielson 7has done/has been doing should give all would-be musicians total freedom of musical expression. Over the last few months Nielson and his team 8have looked/have been looking for a commercial sponsor to take their device to the market. Since January they’ve 9spoken/been speaking to several leading technology firms who seem to be showing interest. ‘You know, I’ve 10always dreamt/always been dreaming that one day something I built could make a huge difference to people’s lives. Now I think I’ve 11managed it/been managing it.’