11.   So Michael Dickinson of the University of California, Berkeley, built a scaled-up set of mechanical wings that have at last revealed how flies stay aloft.

12.   Stamper said Pro Air will be different enough and good enough to stay aloft.

13.   That means, NASA experts say, the aircraft could stay aloft for months or even longer.

14.   The goal is to produce an unmanned aircraft that can stay aloft for months at a time, powered by solar energy and fuel cells.

15.   The hope is only to stay aloft long enough, without too many hurts, until at last the real day comes.

16.   The largest balloons can stay aloft for weeks, repeatedly circling the entire Antarctic continent.

17.   The school went down, the birds stayed aloft.

18.   They also bob up and down annoyingly and stay aloft no more than a week or two.

19.   Will the questions surrounding its airworthiness be immediately answered, or will these initial tests reveal little about how the wood-and-fabric aircraft stayed aloft?

20.   Wind shear is dangerous because it can keep airplanes from maintaining the minimum air speed they need to stay aloft.