Очень нужно ! Choose the correct answer from the words in italics.
As many people know, honey bees 1 (have died / have been dying) in huge numbers over the past few years and this 2 (has been worrying / has worried) scientists. However, engineers at a university in the USA 3 (have worked / have been working) for some time on designs for robotic flying bees and we may soon see these ‘Robobees’ in our skies. Robobees could help by doing the jobs that real bees should be doing.
Over the years scientists 4 (have seen / have been seeing) many failed attempts at making such bees. Researchers on the Robobee project 5 (have had / have been having) many similar problems in the past. They 6 (have created / have been creating) lots of different versions but now believe that, finally, they 7 (have succeeded / have been succeeding) in creating a model that really works. They 8 (have been trying / have tried) for a long time to produce something that is both small and light and it seems that at last they 9 (have managed / have been managing) it. So far a number of countries 10 (have announced / have been announcing) their plans to use Robobees, so their future looks hopeful!
