A textbook introduces some inventions. The first is called "High-Tech Sunglasses". <br/><br/>Later an exercise is proposed to the students: they have to build a dialogue. <br/><br/>"What's your favourite invention?" "My favourite invention is / are the High-Tech Sunglasses." <br/><br/>Now my question is are both alternatives possible, or just one of them? Thank you.<br/><br/>M. G.