已知幂函数y=f（x）的图象过点（2，$\sqrt{2}$），则f（9）=____ 

    It's six forty in the morning. The children are coming into the classroom.

    A girl is opening the windows. Some are laughing and talking. Some are listening to them. Some are reading books. Some are doing their homework.

Miss Lin is standing behind the teacher's desk. She is writing on the blackboard. Sue and Anna are wearing their new dresses today. Ann is cleaning her desk. Mike is helping her. They all look happy.

    What are Bill and Bob doing? Oh, dear! They are still playing basketball.

在图1中，将线段A₁A₂向右平移1个单位到B₁B₂，得到封闭图形A₁A₂B₂B₁（即阴影部分）

在图2中，将线段A₁A₂A₃向右平移1个单位到B₁B₂B₃，得到封闭图形A₁A₂A₃B₃B₂B₁（即阴影部分）

式表示）