Polar bears live in (3) ............... and snow. A polar bear baby is a cub. A cub is born with its eyes closed and does not have much hair. A cub (4) ............... its mother's milk. The cub grows bigger and soon it can walk. The cub likes to play. It rolls in the snow. The cub grows stronger and learns to swim. Its mother shows it how to (5) ............... . When it can find its own (6) ..............., the cub can live by itself. Which is t he best choice for t he blank .......(3).......?