Grt ーー 8
@ Some ocean animals, such as whales, have to sWirn to the surface for
air.② How do they sleep? ③ Surprisingly, they sleep by 0 one halfof
their brain and closing one eye. ③ These animals sleep for several hourS 8
day in all.
⑨ Migratory birds, such as cranes, also sleep in the same Way as whales
during ther long fhghts. ⑨ However, the length of their sleep is not clear.
② Would you jke to sleep and do something at the same time like
hales and cranes?
⑤