1.There'e two brothers.One lives on one side(边),and the other is on the other side.______
3.It lives in a case.When you want to write something,it can help you.______
4.It walks all the time,but never(从不) leaves its place.______
5.It can swim in the water.And it has got a tail(尾巴) and fins(鳍).______
2.It is black when it's clean and white when it isn't clean.______
1.When people say something,they can hear.But they can' t see each other(互相).