A：Hey, Gretel! What can you see on the____? Can you see any bread?

B：No, Hansel．

A：That's too bad．We can't find the pieces of bread．We might be lost．

B：What should we do, Hansel?

A：Take it easy! Be ____! Listen! What can you hear?

B：I can hear a bird's ____．

A：Yeah! The bird ate our bread．____it and then we might find our way．

B：You mean the bird will ____us through the forest．

A：I think so．

B：Great! Let's go!

该图为某区域经纬网图（图中箭头表示地球自转方向），读图判断问题。

在构成人体的结构层次中，人的眼睛属于（　　）