Unit 5 Into the unknown理解课文精研读123451800 BCCentral AmericaMexico1100 AD6Fewer tropical cycloneswetlandsfieldshuge canal systemsexpandeda couple of years789101112131415Some research seems to suggest that the Maya people may have Research indicates that natural disasters may have resulted in thebeen involved in their downfall.decline of the Maya.16Meantime，the rise and fall of this civilisation must also leave us considering our past，present and future.17Thank you for watching!18
