full transcript
"From the Ted Talk by Gillian Gibb: Why can't some birds fly?"

Unscramble the Blue Letters

When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few gtnonereias. Then, over thousands or millions of yaers, the birds’ bodies change to match this new behavior. Their bones, once hollow to minimize weight, become dsene. Their sdtruy feathers turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight mesulcs attach, shrinks or disappears, except in penguins, who repurpose their fhligt muscles and keels for swimming.

Open Cloze

When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few ___________. Then, over thousands or millions of _____, the birds’ bodies change to match this new behavior. Their bones, once hollow to minimize weight, become _____. Their ______ feathers turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight _______ attach, shrinks or disappears, except in penguins, who repurpose their ______ muscles and keels for swimming.

Solution

  1. generations
  2. flight
  3. sturdy
  4. years
  5. dense
  6. muscles

Original Text

When a bird species doesn’t face specific pressures to fly, it can stop flying in as quickly as a few generations. Then, over thousands or millions of years, the birds’ bodies change to match this new behavior. Their bones, once hollow to minimize weight, become dense. Their sturdy feathers turn to fluff. Their wings shrink, and in some cases disappear entirely. And the keel-like protrusion on their sternums, where the flight muscles attach, shrinks or disappears, except in penguins, who repurpose their flight muscles and keels for swimming.

ngrams of length 2

collocation frequency
bird species 4
flightless birds 3

Important Words

  1. attach
  2. behavior
  3. bird
  4. bodies
  5. bones
  6. cases
  7. change
  8. dense
  9. disappear
  10. disappears
  11. face
  12. feathers
  13. flight
  14. fluff
  15. fly
  16. flying
  17. generations
  18. hollow
  19. keels
  20. match
  21. millions
  22. minimize
  23. muscles
  24. penguins
  25. pressures
  26. protrusion
  27. quickly
  28. repurpose
  29. shrink
  30. shrinks
  31. species
  32. specific
  33. sternums
  34. stop
  35. sturdy
  36. swimming
  37. thousands
  38. turn
  39. weight
  40. wings
  41. years