External respiration system Using the lungs and a series of air sacs To communicate with body parts 3. ________ 4. ____sac system Bigger than the lungs

Taking up a 5. ______part of the chest and belly area 6. ______of bird breathing A stream of air

▲going through lungs without 7. ______

▲being channeled through the complex system of air sacs and through 8. ________bones

▲being 9. ______forward through the lungs again，then through more air sacs

▲ 10. ______in the windpipe and are expelled from the body 　　答案：1. water　2. respiration　3. directly/straight　4. Air　5. small　6. Process 7. stopping/stop 8. hollow 9. channeled　10. completing/finishing/ stopping