听力题 Researchers in Troy, New York, have made the world''s smallest brushes, with bristles a thousand times thinner than a human hair. They''re (36) 1to sweep clean the tiny world of nanotechnology. Brushes, brooms and hairy fly swats are probably among the first tools (37) 2 by humans. (38) 3, an ancient paintbrush used by a prehistoric cave artist (39) 4 from 30,000 years ago. So it''s (40) 5 that miniature versions of these should adorn the burgeoning field of nanotechnology. The bristles of these new nanobrushes are made of tiny (41) 6 filaments thirty billionths of a meter across and a few (42) 7long. The brush handles they''re attached to are comparatively large — (43) 8 than a human hair! The researchers have taken microscope pictures (44) 9—particles that would escape any normal brush. The researchers also used their brushes to paint microstructures; and (45) 10. If the tiny tools prove robust enough, (46) 11 or sweeping away unwanted crud.