完形填空。

Mary loves swimming. Every Sunday she has a1lesson with ten  2girls and boys. Their mothers and fathers come  3  them swim because the children are only one or two4old!

When Mary began taking lessons, she was six months old. Now she is one year5and a good swimmer. She can6across the pool and even float on her back. Some people are afraid7the water. Not the children8 Mary's class! They think that swimming9a lot of 10.